Information processing device, analysis method, and analysis program

Abstract

The present invention improves calculation accuracy in the calculation of the Curie temperature for each particle size. An information processing device according to the present invention comprises: a setting unit that acquires particle structure information which indicates the structure of magnetic nanoparticles, first exchange interaction which acts between adjacent atoms of the same type within the magnetic nanoparticles, and second exchange interaction which acts between atoms of the same type in a state in which atoms of different types are arranged therebetween within the magnetic nanoparticles and that sets a magnetic calculation model; a calculation unit that uses the set magnetic calculation model to calculate the magnetization at each temperature, so as to calculate the Curie temperature; and an output unit that associates and outputs the calculated Curie temperature and the particle size of the magnetic nanoparticles included in the particle structure information.

Description

Information processing device, analysis method, and analysis program

[0001] The present disclosure relates to an information processing device, an analysis method, and an analysis program.

[0002] In a recording medium that records data by heat-assisted magnetic recording (HAMR), the recording layer is heated to the Curie temperature of the magnetic nanoparticles that form the recording layer during recording.

[0003] Generally, the Curie temperature varies depending on the particle size of the magnetic nanoparticles, so if the particle sizes of the magnetic nanoparticles that make up the recording layer vary widely, the Curie temperature also varies widely, resulting in a decrease in recording quality.

[0004] For this reason, it is important to measure the particle size variation of the magnetic nanoparticles that form the recording layer in advance and to control the range of the Curie temperature of the magnetic nanoparticles that form the recording layer in order to quantitatively indicate the recording quality.

[0005] NTBinh, RWChantrell, et al. "Influence of finite-size effects on the Curie temperature of L10-FePt.", Physical Review B 106.5(2022):054421

[0006] Here, the Curie temperature for each particle size of magnetic nanoparticles can be calculated using magnetic simulation software, but conventional magnetic simulation software did not have sufficient calculation accuracy to strictly control the range of Curie temperatures.

[0007] The present disclosure improves the accuracy of calculation when calculating the Curie temperature for each particle size.

[0008] An information processing device according to a first aspect of the present disclosure includes: a setting unit that acquires particle structure information indicating the structure of a magnetic nanoparticle, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticle, and a second exchange interaction acting between atoms of the same type in a state in which atoms of different types are arranged between them within the magnetic nanoparticle, and sets a magnetic calculation model; a calculation unit that calculates the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; and an output unit that outputs the particle size of the magnetic nanoparticle included in the particle structure information in association with the calculated Curie temperature.

[0009] A second aspect of the present disclosure is the information processing device according to the first aspect, wherein the particle structure information further includes atomic arrangement information indicating an arrangement of atoms contained in the magnetic nanoparticles.

[0010] A third aspect of the present disclosure is an information processing device according to the second aspect, wherein the setting unit acquires, as the first exchange interaction, an exchange interaction acting between adjacent atoms in the same plane among atoms arranged based on the atomic arrangement information, and acquires, as the second exchange interaction, an exchange interaction acting between atoms of the same type in a direction perpendicular to the same plane among atoms arranged based on the atomic arrangement information.

[0011] A fourth aspect of the present disclosure is an information processing device according to the first aspect, wherein when the setting unit sequentially sets a plurality of magnetic calculation models in which the particle sizes of the magnetic nanoparticles are different from each other and the calculation unit sequentially calculates the Curie temperatures, the output unit calculates a range of Curie temperatures corresponding to a predetermined range of particle sizes.

[0012] A fifth aspect of the present disclosure is the information processing device according to the fourth aspect, wherein the output unit outputs a graph showing the relationship between the particle sizes of the magnetic nanoparticles and the calculated Curie temperatures.

[0013] A sixth aspect of the present disclosure is the information processing device according to the fifth aspect, wherein the output unit outputs the particle size range and the Curie temperature range superimposed on the graph.

[0014] A seventh aspect of the present disclosure is the information processing device according to the fourth aspect, wherein the particle size range is identified based on a median value and a variance value of the particle sizes.

[0015] An eighth aspect of the present disclosure is the information processing device according to any one of the first to seventh aspects, wherein the magnetic nanoparticles are FePt magnetic nanoparticles.

[0016] A ninth aspect of the present disclosure is the information processing device according to the eighth aspect, wherein the first exchange interaction is an exchange interaction acting between Fe atoms, and the second exchange interaction is an exchange interaction acting between Fe atoms with a Pt atom disposed therebetween.

[0017] A tenth aspect of the present disclosure is the information processing device according to any one of the first to ninth aspects, wherein the first exchange interaction and the second exchange interaction are calculated by first-principles calculation.

[0018] An analysis method according to an eleventh aspect of the present disclosure includes a computer that performs the following steps: acquiring particle structure information indicating the structure of a magnetic nanoparticle, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticle, and a second exchange interaction acting between atoms of the same type with different types of atoms arranged between them within the magnetic nanoparticle, and setting up a magnetic calculation model; calculating the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; and outputting the particle size of the magnetic nanoparticle included in the particle structure information in association with the calculated Curie temperature.

[0019] An analysis program according to a twelfth aspect of the present disclosure causes a computer to perform the following steps: acquire particle structure information indicating the structure of a magnetic nanoparticle, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticle, and a second exchange interaction acting between atoms of the same type in a state in which atoms of different types are arranged between them within the magnetic nanoparticle, and set up a magnetic calculation model; calculate the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; and output the particle size of the magnetic nanoparticle included in the particle structure information in association with the calculated Curie temperature.

[0020] According to the present disclosure, it is possible to improve the calculation accuracy when calculating the Curie temperature for each particle size.

[0021] FIG. 1 is a first diagram showing an example of the system configuration of an analysis system. FIG. 2A is a diagram showing the relationship between temperature and magnetization. FIG. 2B is a diagram showing an example of a method for calculating the Curie temperature. FIG. 3 is a diagram for explaining an overview of a magnetic calculation model. FIG. 4 is a diagram showing an example of the hardware configuration of an information processing device. FIG. 5 is a diagram showing an example of the functional configuration of an information processing device. FIG. 6 is a first flowchart showing the flow of a Curie temperature range calculation process. FIG. 7 is a diagram showing an example of stored data. FIG. 8 is a diagram showing a graph showing the relationship between particle size and Curie temperature, with the particle size range and the Curie temperature range superimposed on it. FIG. 9A is a first diagram showing differences in calculation accuracy due to differences in magnetic calculation models. FIG. 9B is a second diagram showing differences in calculation accuracy due to differences in magnetic calculation models. FIG. 10 is a second diagram showing an example of the system configuration of an analysis system. FIG. 11 is a second flowchart showing the flow of a Curie temperature range calculation process.

[0022] Hereinafter, each embodiment will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0023] [First Embodiment] <System Configuration of Analysis System> First, the system configuration of an analysis system including an information processing device according to the first embodiment will be described. Fig. 1 is a first diagram showing an example of the system configuration of an analysis system. As shown in Fig. 1, a target device on which an analysis target to be analyzed by the analysis system 100 is arranged is a magnetic storage device 130. The magnetic storage device 130 has a thermally assisted magnetic recording medium 131, a magnetic recording medium driver 132 for rotating the thermally assisted magnetic recording medium 131, and a recording head 133.

[0024] Reference numeral 140 indicates the positional relationship of each part around the recording head 133. As indicated by reference numeral 140, the recording head 133 has a laser element 141 and irradiates the recording layer 143 with near-field light 142. This heats the recording layer 143 to its Curie temperature, making it possible to record data at a high recording density in the thermally assisted magnetic recording medium 131. In the first embodiment, the recording layer 143 is formed of FePt magnetic nanoparticles.

[0025] Reference numeral 150 denotes an enlarged view of the surface of the recording layer 143, and each particle separated by a white line represents an FePt magnetic nanoparticle. The double-headed arrow in reference numeral 150 indicates the particle size of one FePt magnetic nanoparticle.

[0026] The analysis system 100 calculates the range of Curie temperatures of FePt magnetic nanoparticles forming the recording layer 143 of the thermally assisted magnetic recording medium 131 used in the magnetic storage device 130. This makes it possible to quantitatively indicate the recording quality of the recording layer 143.

[0027] Specifically, the measuring device 110 of the analysis system 100 measures in advance the particle size of a sample of FePt magnetic nanoparticles that form the recording layer 143 of the thermally assisted magnetic recording medium 131 used in the magnetic storage device 130. The measuring device 110 of the analysis system 100 calculates the median and variance of the particle size as information indicating the variation in the particle size of the measured sample, and notifies the information processing device 120 of the results.

[0028] An analysis program is installed in the information processing device 120 of the analysis system 100, and by executing the analysis program, the information processing device 120 functions as a setting unit 121, a Curie temperature calculation unit 122, and an output unit 123.

[0029] The setting unit 121 acquires setting information required to set a magnetic calculation model for one FePt magnetic nanoparticle, and sets the magnetic calculation model.

[0030] The Curie temperature calculation unit 122 performs a magnetic simulation process using the set magnetic calculation model, and calculates the average magnetization of the entire magnetic calculation model at each temperature, thereby calculating the Curie temperature.

[0031] The output unit 123 outputs the particle size of the magnetic calculation model included in the setting information in association with the calculated Curie temperature.

[0032] Specifically, when the Curie temperature calculation unit 122 sequentially calculates the Curie temperature for each of multiple magnetic calculation models having different particle sizes, the output unit 123 outputs a graph showing the relationship between multiple particle sizes and multiple Curie temperatures.

[0033] Furthermore, when information indicating the variation in particle size is notified by the measuring device 110, the output unit 123 calculates the range of particle sizes based on the information indicating the variation in particle size. Subsequently, the output unit 123 calculates the range of Curie temperatures corresponding to the range of particle sizes based on the graph. This allows the output unit 123 to output the range of particle sizes and the range of Curie temperatures superimposed on the graph.

[0034] <Relationship Between Temperature and Magnetization> Next, the relationship between the magnetization calculated using the magnetic calculation model and the temperature will be described. Fig. 2A is a diagram showing the relationship between the temperature and the magnetization. In Fig. 2A, the horizontal axis represents the temperature [K], and the vertical axis represents the average magnetization [M]. Graph 210 shows the average magnetization at each temperature of the magnetic calculation model.

[0035] Reference numeral 221 indicates the magnetism of each atom in the magnetic calculation model at a temperature of 0 [K], reference numeral 222 indicates the magnetism of each atom in the magnetic calculation model at a temperature of 500 [K], and reference numeral 223 indicates the magnetism of each atom in the magnetic calculation model at a temperature of 620 [K]. Note that the spheres arranged within reference numerals 221 to 223 each represent one atom, and dark-colored atoms indicate that the magnetic force is oriented in a specific direction. Light-colored atoms indicate that the magnetic force is oriented in multiple directions.

[0036] 2B is a diagram showing an example of a method for calculating the Curie temperature. In FIG. 2B, a graph 230 shows the result of fitting a mathematical formula (described later) to the graph 210. The Curie temperature calculation unit 122 calculates the Curie temperature by fitting the relationship between the temperature and the average magnetization.

[0037] <Outline of Magnetic Calculation Model> Next, an outline of the magnetic calculation model will be described. Here, first, as a comparative example, an outline of a magnetic calculation model in which it is difficult to achieve sufficient calculation accuracy by the Curie temperature calculation unit 122 will be described. Next, an outline of a magnetic calculation model in which it is possible to achieve sufficient calculation accuracy by the Curie temperature calculation unit 122 will be described.

[0038] 3A and 3B are diagrams for explaining an outline of the magnetic calculation model, in which 3A in Fig. 3 shows the flow of processing up to setting the magnetic calculation model of the comparative example.

[0039] In Fig. 3A, reference numeral 310 denotes the arrangement of Fe atoms and Pt atoms in an FePt magnetic nanoparticle. In Fig. 3A, reference numeral 320 denotes a simplified arrangement within an FePt magnetic nanoparticle in order to reduce calculation costs when setting up a magnetic calculation model for the FePt magnetic nanoparticle. Specifically, the example in Fig. 3A shows an arrangement of only Fe atoms on a simple cubic lattice.

[0040] In Fig. 3A, reference numeral 330 denotes a magnetic calculation model for one particle of FePt magnetic nanoparticle of a predetermined particle size, in which only Fe atoms are arranged on a simple cubic lattice. In the example of Fig. 3A, the particle size of the magnetic calculation model is set to 3 × 3 × 3 particles due to space limitations.

[0041] In FIG. 3A, reference numeral 340 indicates that "J" is set as the exchange interaction acting between adjacent Fe atoms in the set magnetic calculation model. Regarding conventional magnetic simulation software, for example, the software creator has published a paper described in the reference document below. Referring to this paper, it is described that for a magnetic calculation model of FePt magnetic nanoparticles, only one type of value is set as the exchange interaction acting between atoms. Therefore, according to this paper, in the case of the magnetic calculation model of the comparative example, as shown by reference numeral 340, only one type of value is set as the exchange interaction acting between atoms, regardless of the direction in which the adjacent atoms are located.

[0042] [Reference] Binh Thanh Nguyen, Sergiu Ruta, Ondrej Hovorka, Richard. FL Evans, Roy. W. Chantrell, "Influence of finite-size effects on the Curie temperature of L10-FePt", Phys. Rev,B106, 054421-Published 17, August 2022<https: / / doi.org / 10.48550 / arXiv.2207.11831> In the example of reference numeral 340, due to space limitations, only the Fe atom indicated by reference numeral 341 and the Fe atoms adjacent to the Fe atom indicated by reference numeral 341 (reference numerals 342 to 347) are shown among the Fe atoms included in the magnetic calculation model, and only the exchange interaction acting between the Fe atom indicated by reference numeral 341 and the Fe atoms adjacent to the Fe atom indicated by reference numeral 341 (reference numerals 342 to 347) is shown as the exchange interaction.

[0043] However, for Fe atoms other than the Fe atom indicated by reference numeral 341, "J" is set as the exchange interaction acting between the Fe atoms and the adjacent Fe atoms, similarly to the example of reference numeral 340.

[0044] In contrast to this, 3b in FIG. 3 shows a flow up to setting a magnetic calculation model that can achieve sufficient calculation accuracy by the Curie temperature calculation unit 122.

[0045] In FIG. 3B, the reference numerals 310 to 330 are the same as the reference numerals 310 to 330 in FIG. 3A, and therefore the description thereof will be omitted here.

[0046] In the case of the setting unit 121 of the information processing device 120 according to the first embodiment, at least two different values ​​can be set as the exchange interaction acting between atoms depending on the direction in which adjacent atoms are located.

[0047] In FIG. 3 b, reference numeral 350 indicates a state in which, in the magnetic calculation model, "J'" is set as the first exchange interaction acting between adjacent Fe atoms (reference numerals 342 to 345) in the same plane 351, and "J" is set as the second exchange interaction acting between adjacent Fe atoms (reference numerals 346 and 347) arranged at positions perpendicular to the same plane 351. However, it is assumed that there is a relationship of "J'" > "J". Here, the reason why "J'" > "J" is that, in setting the magnetic calculation model, a configuration in which only Fe atoms are arranged is adopted for simplification, but a Pt atom is actually arranged between the Fe atom indicated by reference numeral 341 and the Fe atom indicated by reference numeral 346. In other words, the exchange interaction acting between the Fe atoms (reference numerals 346 and 347) with a Pt atom, which is a different type of atom, arranged between them is smaller than the exchange interaction acting between the Fe atoms (reference numerals 342 to 345) without a Pt atom arranged between them.

[0048] In this way, the information processing device 120 according to the first embodiment is configured as follows when setting up a magnetic calculation model: - to reduce calculation costs by arranging only Fe atoms on a simple cubic lattice, while - to provide an effect similar to that of arranging Pt atoms by differentiating the exchange interaction acting between atoms of the same type (between Fe atoms) between when the interaction is within the same plane 351 and when the interaction is in a direction perpendicular to the same plane 351. As a result, the information processing device 120 according to the first embodiment can improve the calculation accuracy in calculating the Curie temperature.

[0049] <Hardware Configuration of Information Processing Device> Next, the hardware configuration of the information processing device 120 will be described. Fig. 4 is a diagram showing an example of the hardware configuration of the information processing device. As shown in Fig. 4, the information processing device 120 has a processor 401, a memory 402, an auxiliary storage device 403, an I / F (Interface) device 404, a communication device 405, and a drive device 406. Note that the respective hardware components of the information processing device 120 are connected to each other via a bus 407.

[0050] The processor 401 has various arithmetic devices such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc. The processor 401 reads various programs (for example, an analysis program) into the memory 402 and executes the programs.

[0051] The memory 402 has a main storage device such as a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The processor 401 and the memory 402 form a so-called computer, and the processor 401 executes various programs read onto the memory 402, thereby enabling the computer to realize various functions.

[0052] The auxiliary storage device 403 stores various programs and various data used when the various programs are executed by the processor 401. For example, a data storage unit 535 (described later) is realized in the auxiliary storage device 403.

[0053] The I / F device 404 is a connection device for connecting an operation device 411, which is an example of a user interface device, and a display device 412. The communication device 405 is a communication device for communicating with an external device via a network (not shown).

[0054] The drive device 406 is a device for setting a recording medium 413. The recording medium 413 here includes media that record information optically, electrically, or magnetically, such as a CD-ROM, a flexible disk, a magneto-optical disk, etc. The recording medium 413 may also include semiconductor memories that record information electrically, such as ROMs, flash memories, etc.

[0055] The various programs to be installed in the auxiliary storage device 403 are installed, for example, by setting the distributed recording medium 413 in the drive device 406 and reading the various programs recorded on the recording medium 413 by the drive device 406. Alternatively, the various programs to be installed in the auxiliary storage device 403 may be installed when downloaded from a network via the communication device 405.

[0056] <Functional Configuration of Information Processing Apparatus> Next, a detailed description will be given of the functional configuration of the information processing apparatus 120. Fig. 5 is a diagram showing an example of the functional configuration of the information processing apparatus.

[0057] As shown in FIG. 5, the setting unit 121 further includes a particle structure information acquisition unit 511 , an exchange interaction information acquisition unit 512 , and a magnetic calculation model setting unit 513 .

[0058] The particle structure information acquisition unit 511 and the exchange interaction information acquisition unit 512 acquire setting information necessary to identify a magnetic calculation model for one FePt magnetic nanoparticle particle that is the target of magnetic simulation. The setting information acquired by the information processing device 120 includes at least atomic arrangement information, particle size, particle shape, first exchange interaction, and second exchange interaction.

[0059] The particle structure information acquisition unit 511 acquires the atomic arrangement information, particle size, and particle shape of the FePt magnetic nanoparticles from the above setting information. The information processing device 120 according to the first embodiment sets the simplified magnetic calculation model shown in 3b of Fig. 3 and executes the magnetic simulation process. For this reason, the particle structure information acquisition unit 511 acquires, for example, atomic arrangement information: only Fe atoms are arranged as N atoms on a simple cubic lattice with an interatomic distance L. ２ Array of particles - Particle size, particle shape: A cubic shape with one side measuring (N-1) x L is obtained.

[0060] The exchange interaction information acquisition unit 512 acquires the first exchange interaction and the second exchange interaction from the setting information. As described in 3b of Figure 3, in the case of the information processing device 120 according to the first embodiment, the exchange interaction information acquisition unit 512 acquires the first exchange interaction = J' and the second exchange interaction = J" (where J' > J").

[0061] The magnetic calculation model setting unit 513 identifies a magnetic calculation model based on the setting information acquired by the particle structure information acquisition unit 511 and the exchange interaction information acquisition unit 512 , and sets the model in the Curie temperature calculation unit 122 .

[0062] As shown in FIG. 5, the Curie temperature calculation unit 122 further includes a temperature control unit 521 , a magnetic calculation model 522 , an average magnetization calculation unit 523 , and a determination unit 524 .

[0063] The temperature control unit 521 controls the temperature value to be applied to the magnetic calculation model 522 during magnetic simulation processing.

[0064] The magnetic calculation model 522 is a magnetic calculation model set by the magnetic calculation model setting unit 513, and calculates the magnetism of each atom (the direction of the magnetic moment of each atom, the direction of magnetization of each atom) at each temperature controlled by the temperature control unit 521.

[0065] The average magnetization calculation unit 523 calculates the average magnetization of the entire magnetic calculation model at each temperature, i.e., the average magnetization of the entire particle, from the magnetization of each atom calculated by performing magnetic simulation processing using the magnetic calculation model 522.

[0066] The determining unit 524 calculates the Curie temperature by fitting the plot of the average magnetization and the temperature using the following equation 1.

[0067] where T is temperature, T Ｃ : Curie temperature, β≈0.34.

[0068] As shown in FIG. 5, the output unit 123 further includes a Curie temperature acquisition unit 531 , a particle size acquisition unit 532 , a temperature range calculation unit 533 , and a graphing unit 534 .

[0069] When the Curie temperature calculation unit 122 completes the magnetic simulation process, the Curie temperature acquisition unit 531 acquires the Curie temperature from the Curie temperature calculation unit 122 and stores it in the data storage unit 535. Note that the Curie temperature acquisition unit 531 acquires the Curie temperatures for a plurality of magnetic calculation models 522 having different particle sizes as targets of magnetic simulation, and stores them in the data storage unit 535 as storage data.

[0070] The particle size acquisition unit 532 acquires the particle size of the magnetic calculation model 522, associates it with the Curie temperature, and stores it as storage data in the data storage unit 535. Note that the particle size acquisition unit 532 sequentially acquires the particle size of each of the multiple magnetic calculation models 522, which have different particle sizes from one another, during the magnetic simulation process. Each time the Curie temperature acquisition unit 531 acquires a Curie temperature, the particle size acquisition unit 532 associates the sequentially acquired particle size with the acquired Curie temperature and stores it as storage data in the data storage unit 535.

[0071] The temperature range calculation unit 533 calculates the range of particle sizes based on the information indicating the variation in particle sizes notified from the measurement device 110. Specifically, the temperature range calculation unit 533 calculates the range of particle sizes using the median and variance included in the information indicating the variation in particle sizes. The particle size range calculated by the temperature range calculation unit 533 includes the median, median-variance / 2, and median+variance / 2.

[0072] The temperature range calculation unit 533 calculates a range of Curie temperatures corresponding to a range of particle sizes based on a plurality of combinations of Curie temperatures and particle sizes stored in the data storage unit 535. The range of Curie temperatures calculated by the temperature range calculation unit 533 includes: a Curie temperature corresponding to the median particle size; a Curie temperature corresponding to the median particle size - the variance / 2; and a Curie temperature corresponding to the median particle size + the variance / 2. The temperature range calculation unit 533 notifies the graphing unit 534 of the range of particle sizes and the range of Curie temperatures.

[0073] The graphing unit 534 reads out a plurality of combinations of Curie temperature and particle size stored in the data storage unit 535 and generates a graph. The graphing unit 534 outputs the particle size range and the Curie temperature range notified by the temperature range calculation unit 533 by superimposing them on the generated graph.

[0074] <Flow of Curie Temperature Range Calculation Processing> Next, a description will be given of the flow of Curie temperature range calculation processing by the analysis system 100. Fig. 6 is a first flowchart showing the flow of Curie temperature range calculation processing.

[0075] In step S601, the measuring device 110 measures the particle size of a sample of FePt magnetic nanoparticles to be applied to the target device and calculates information indicating the variation in particle size. The information processing device 120 acquires the calculated information indicating the variation in particle size and calculates the range of particle size.

[0076] In step S602, the information processing device 120 receives input of the first exchange interaction and the second exchange interaction of the FePt magnetic nanoparticles from the user, thereby acquiring the first exchange interaction and the second exchange interaction of the FePt magnetic nanoparticles.

[0077] In step S603, the information processing device 120 acquires, from the user, atomic arrangement information, particle size, particle shape, and the like as particle structure information of the magnetic calculation model for one FePt magnetic nanoparticle.

[0078] In step S604, the information processing device 120 sets a magnetic calculation model for one FePt magnetic nanoparticle particle identified based on setting information including: the first exchange interaction and the second exchange interaction acquired in step S602; and particle structure information acquired in step S603.

[0079] In step S605, the information processing device 120 executes a magnetic simulation process using the set magnetic calculation model, and calculates the average magnetization at each temperature.

[0080] In step S606, the information processing device 120 calculates the Curie temperature based on the calculated average magnetization.

[0081] In step S607, the information processing device 120 determines whether or not to execute magnetic simulation processing for other particle sizes. If it is determined in step S607 that magnetic simulation processing is to be executed for other particle sizes (YES in step S607), the process returns to step S603. In this case, in step S603, the information processing device 120 acquires particle structure information including the other particle sizes, and executes the processing of steps S604 to S607 by sequentially setting multiple magnetic calculation models with different particle sizes. This allows the information processing device 120 to sequentially calculate the Curie temperature corresponding to each particle size.

[0082] On the other hand, if it is determined in step S607 that the magnetic simulation process is not to be performed for other particle sizes (NO in step S607), the process proceeds to step S608.

[0083] In step S608, the information processing device 120 calculates the range of Curie temperatures corresponding to the range of particle sizes calculated in step S601.

[0084] In step S609, the information processing device 120 repeats the processes of steps S603 to S607, and acquires multiple combinations of particle sizes and Curie temperatures generated by executing magnetic simulation processes for different particle sizes. The information processing device 120 generates a graph based on the multiple acquired combinations of particle sizes and Curie temperatures. The information processing device 120 outputs the generated graph by superimposing the particle size range calculated in step S601 and the Curie temperature range calculated in step S608 on it.

[0085] <Specific Example of Stored Data> Next, a description will be given of a specific example of stored data stored in the data storage unit 535. Fig. 7 is a diagram showing an example of stored data.

[0086] As shown in FIG. 7 , the stored data 700 includes information items such as "particle size [nm]" and "Curie temperature [K]." The "particle size [nm]" stores the particle size included in the particle structure information sequentially acquired by the particle structure information acquisition unit 511. The "Curie temperature [K]" stores the Curie temperature sequentially calculated by the Curie temperature calculation unit 122 in association with the particle size.

[0087] <Specific Example of Graph> Next, a description will be given of a specific example of a graph generated by the graphing unit 534. Fig. 8 shows a graph showing the relationship between particle size and Curie temperature, with the particle size range and the Curie temperature range superimposed on it.

[0088] 8, the horizontal axis represents particle size [nm] and the vertical axis represents Curie temperature [K]. Reference numeral 801 in graph 800 represents the median value of the particle size of the FePt magnetic nanoparticles measured by the measurement device 110. Reference numeral 802 in graph 800 represents the particle size obtained by adding or subtracting 1 / 2 of the dispersion value δD of the particle size of the FePt magnetic nanoparticles measured by the measurement device 110 to or from the median value.

[0089] Reference numeral 811 in graph 800 represents the Curie temperature at the intersection of the straight line 801 representing the median value of the particle size and the curve 820 representing the Curie temperature. Reference numeral 812 in graph 800 represents the Curie temperature at the intersection of the straight line 802 representing the particle size obtained by adding or subtracting ½ of the particle size dispersion value δD to or from the median value and the curve 820 representing the Curie temperature.

[0090] That is, the range enclosed by the lines indicated by the reference numeral 802 represents the range of particle sizes, and the range enclosed by the lines indicated by the reference numeral 812 represents the range of Curie temperatures.

[0091] <Explanation of Calculation Accuracy> Next, differences in the calculation accuracy of the Curie temperature due to differences in the set magnetic calculation model will be described. Fig. 9A is a first diagram showing differences in calculation accuracy due to differences in the magnetic calculation model. In a graph 900 shown in Fig. 9A, the horizontal axis represents particle size [nm] and the vertical axis represents Curie temperature [K].

[0092] The reference numerals 901 and 902 in the graph 800 indicate the results of a magnetic simulation performed using: a simple cubic lattice magnetic calculation model; and a magnetic calculation model in which the Curie temperature is 750 K when the particle size is 12 nm. The reference numeral 901 indicates a comparative example in which the magnetic simulation was performed using a magnetic calculation model in which "J" is set as the exchange interaction acting between adjacent Fe atoms, as shown in 3a of FIG. 3. On the other hand, the reference numeral 902 indicates a comparative example in which the magnetic simulation was performed using a magnetic calculation model in which "J'" is set as the first exchange interaction and "J"" is set as the second exchange interaction, as shown in 3b of FIG. 3.

[0093] Comparing reference numeral 901 and reference numeral 902, as the particle size becomes smaller, the Curie temperature decreases more significantly for reference numeral 902, while the Curie temperature decreases less significantly for reference numeral 901. Note that the experimental values ​​of the Curie temperature for each particle size show a larger decrease in Curie temperature as the particle size becomes smaller, and are closer to the value for reference numeral 902.

[0094] Figure 9B is a second diagram showing the difference in calculation accuracy due to differences in magnetic calculation models, and shows a comparison between: - the Curie temperature calculated from the average magnetization measured when FePt magnetic nanoparticles were actually heated; and - the Curie temperature calculated from the average magnetization calculated by performing a magnetic simulation using a magnetic calculation model that reproduces the FePt magnetic nanoparticles.

[0095] 9B, "Summary of particle sizes of FePt magnetic nanoparticles used in the experiment" refers to the FePt magnetic nanoparticles used in the experiment analyzed using a TEM, and the particle sizes in the planar and cross-sectional directions were tabulated. Note that TEM is an abbreviation for Transmission Electron Microscope, and refers to a transmission electron microscope.

[0096] Also, in reference to the reference numeral 910 in Figure 9B, "Summary of Curie temperature obtained from measurement data" refers to the Curie temperature calculated from the average magnetization measured when the FePt magnetic nanoparticles were actually heated, and the variance value of the Curie temperature.

[0097] On the other hand, reference numeral 911 in FIG. 9B shows an overview of the Curie temperature when a magnetic simulation process is performed using a magnetic calculation model in which “J” is set as the exchange interaction acting between adjacent Fe atoms (comparative example).

[0098] Also, reference numeral 912 in Figure 9B shows an overview of the Curie temperature when a magnetic simulation process is performed (this method) using a magnetic calculation model in which "J'" is set as the first exchange interaction and "J"" is set as the second exchange interaction.

[0099] Comparing reference numerals 911 and 912, the variance of the Curie temperature of reference numeral 911 deviates from the variance of the Curie temperature of reference numeral 910, whereas the variance of the Curie temperature of reference numeral 912 is included in the variance of the Curie temperature of reference numeral 910.

[0100] In this way, when comparing the following cases, it was verified from Figures 9A and 9B that the former case can achieve higher calculation accuracy in calculating the Curie temperature: - a case where a magnetic calculation model is used in which "J'" is set as the first exchange interaction and "J" is set as the second exchange interaction; and - a case where a magnetic calculation model is used in which "J" is set as the exchange interaction.

[0101] <Summary> As is clear from the above explanation, the information processing device 120 according to the first embodiment: - acquires particle structure information indicating the structure of FePt magnetic nanoparticles, a first exchange interaction acting between Fe atoms contained in the FePt magnetic nanoparticles, and a second exchange interaction acting between Fe atoms in a state where Pt is interposed within the FePt magnetic nanoparticles; - sets a magnetic calculation model using the acquired particle structure information, the first exchange interaction, and the second exchange interaction; - performs a magnetic simulation process using the set magnetic calculation model, and calculates the Curie temperature by calculating the average magnetization at each temperature; - generates and outputs a graph showing the relationship between the particle size of the magnetic nanoparticles included in the particle structure information and the calculated Curie temperature.

[0102] In this way, by performing a magnetic simulation process using a magnetic calculation model in which the first exchange interaction and the second exchange interaction are set, it is possible to calculate the Curie temperature with high calculation accuracy. In other words, according to the first embodiment, it is possible to improve the calculation accuracy in calculating the Curie temperature for each particle size.

[0103] Second Embodiment In the first embodiment, no mention is made of a method for calculating the first exchange interaction "J'" and the second exchange interaction "J", but the first exchange interaction and the second exchange interaction may be calculated by first-principles calculation. Hereinafter, the second embodiment will be described, focusing on the differences from the first embodiment.

[0104] <System Configuration of Analysis System> First, the system configuration of an analysis system including an information processing device according to the second embodiment will be described. Fig. 10 is a second diagram showing an example of the system configuration of the analysis system. The difference from the system configuration described using Fig. 1 in the first embodiment is that the analysis system 1000 includes an information processing device 1010.

[0105] A first-principles calculation program is installed in the information processing device 1010, and the information processing device 1010 functions as a first-principles calculation unit 1011 by executing the program.

[0106] Information about the FePt magnetic particle crystal is input to the first-principles calculation unit 1011. This allows the first-principles calculation unit 1011 to calculate the first exchange interaction and the second exchange interaction of the FePt magnetic nanoparticle by first-principles calculation.

[0107] For example, the first-principles calculation unit 1011 calculates the first exchange interaction as J′=9.54×10 －２１ [J / link] is the second exchange interaction, J" = 0.90 × 10 －２１ [J / link] can be calculated.

[0108] The first and second exchange interactions calculated by the first-principles calculation unit 1011 are used as part of the setting information input to the information processing device 120 .

[0109] <Flow of Curie Temperature Range Calculation Processing> Next, a description will be given of the flow of Curie temperature range calculation processing by analysis system 1000. Fig. 11 is a second flowchart showing the flow of Curie temperature range calculation processing. The difference from the flowchart described with reference to Fig. 5 in the first embodiment is steps S1101 to S1103.

[0110] In step S1101, the information processing device 1010 receives input of information relating to FePt magnetic particle crystals.

[0111] In step S1102, the information processing device 1010 optimizes the crystal structure by first-principles calculation.

[0112] In step S1103, the information processing device 1010 calculates the first exchange interaction and the second exchange interaction of the FePt magnetic nanoparticles by first-principles calculation.

[0113] <Summary> As is clear from the above description, the information processing device 120 according to the second embodiment has the same functions as the information processing device 120 according to the first embodiment. When acquiring the first exchange interaction and the second exchange interaction, the information processing device 1010 is used to acquire the first exchange interaction and the second exchange interaction calculated by first-principles calculation.

[0114] As a result, the information processing device 120 according to the second embodiment can further improve the calculation accuracy in calculating the Curie temperature for each particle size.

[0115] [Other Embodiments] In each of the above embodiments, the Curie temperature calculation unit 122 is configured to calculate the Curie temperature each time the user changes the particle size. However, the method of setting the particle size is not limited to this. For example, multiple particle sizes may be set collectively as the particle size of the magnetic calculation model to be subjected to magnetic simulation. In this case, the Curie temperature calculation unit 122 may be configured to sequentially calculate the Curie temperature for each of the multiple particle sizes that have been set.

[0116] The setting unit 121 may be configured to receive input of each of a plurality of particle sizes, or may be configured to receive input of the maximum and minimum values ​​and step widths of a plurality of particle sizes. In this case, the maximum and minimum values ​​of the particle size may be determined based on, for example, the range of particle sizes.

[0117] Furthermore, in each of the above embodiments, the information processing device 120 has been described as outputting the range of Curie temperatures in order to quantitatively indicate the recording quality of the recording layer 143. However, the method of using the range of Curie temperatures output by the information processing device 120 is not limited to this.

[0118] For example, the particle shape included in the setting information may be changed and the range of Curie temperatures for each particle shape may be calculated to search for the optimal particle shape of the FePt magnetic nanoparticles. The particle shapes here include, for example, square prisms, cylinders, hexagonal prisms, etc.

[0119] Alternatively, the optimum magnetic nanoparticles may be searched for by inputting setting information specifying magnetic nanoparticles other than FePt magnetic nanoparticles and calculating the range of Curie temperatures for each type of magnetic nanoparticle.

[0120] Furthermore, in the second embodiment, the information processing device 1010 and the information processing device 120 are configured as separate devices, but the information processing device 1010 and the information processing device 120 may be configured as an integrated device.

[0121] The present invention is not limited to the configurations described in the above embodiments, but may be combined with other elements, etc. These aspects can be changed without departing from the spirit of the present invention, and can be appropriately determined depending on the application form.

[0122] This application claims priority based on Japanese Patent Application No. 2023-200999, filed on November 28, 2023, the entire contents of which are incorporated herein by reference.

[0123] 100: Analysis system 110: Measuring device 120: Information processing device 121: Setting unit 122: Curie temperature calculation unit 123: Output unit 511: Grain structure information acquisition unit 512: Exchange interaction information acquisition unit 513: Magnetic calculation model setting unit 521: Temperature control unit 522: Magnetic calculation model 523: Average magnetization calculation unit 531: Curie temperature acquisition unit 532: Grain size acquisition unit 533: Temperature range calculation unit 534: Graphing unit 800: Graph 1010: Information processing device 1011: First-principles calculation unit

Claims

1. a setting unit that acquires particle structure information indicating the structure of a magnetic nanoparticle, a first exchange interaction that acts between adjacent atoms of the same type within the magnetic nanoparticle, and a second exchange interaction that acts between atoms of the same type in a state where atoms of different types are arranged between them within the magnetic nanoparticle, and sets a magnetic calculation model; a calculation unit that calculates the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; an output unit that outputs the particle size of the magnetic nanoparticles included in the particle structure information in association with the calculated Curie temperature; An information processing device having the above.

2. The information processing device according to claim 1 , wherein the particle structure information further includes atomic arrangement information indicating an arrangement of atoms contained in the magnetic nanoparticles.

3. The setting unit As the first exchange interaction, an exchange interaction acting between adjacent atoms on the same plane among atoms arranged based on the atomic arrangement information is acquired; The information processing device according to claim 2 , wherein, as the second exchange interaction, an exchange interaction acting between atoms of the same type in a direction perpendicular to the same plane among atoms arranged based on the atomic arrangement information is acquired.

4. When the setting unit sequentially sets a plurality of magnetic calculation models in which the particle sizes of the magnetic nanoparticles are different from each other and the calculation unit sequentially calculates the Curie temperatures, the output unit calculates a range of Curie temperatures corresponding to a predetermined range of particle sizes. The information processing device according to claim 1 .

5. The information processing device according to claim 4 , wherein the output unit outputs a graph showing a relationship between particle sizes of the magnetic nanoparticles and the calculated Curie temperatures.

6. The information processing device according to claim 5 , wherein the output unit outputs the particle size range and the Curie temperature range superimposed on the graph.

7. The information processing device according to claim 4 , wherein the range of particle sizes is specified based on a median value and a variance value of particle sizes.

8. The information processing device according to claim 1 , wherein the magnetic nanoparticles are FePt magnetic nanoparticles.

9. 9. The information processing device according to claim 8, wherein the first exchange interaction is an exchange interaction acting between Fe atoms, and the second exchange interaction is an exchange interaction acting between Fe atoms with Pt atoms interposed therebetween.

10. The information processing device according to claim 1 , wherein the first exchange interaction and the second exchange interaction are calculated by first-principles calculation.

11. The computer A process of acquiring particle structure information indicating the structure of a magnetic nanoparticle, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticle, and a second exchange interaction acting between atoms of the same type in a state where atoms of different types are arranged between them within the magnetic nanoparticle, and setting up a magnetic calculation model; a step of calculating the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; a step of outputting the particle size of the magnetic nanoparticles included in the particle structure information in association with the calculated Curie temperature; The analysis method to perform.

12. On the computer, A process of acquiring particle structure information indicating the structure of a magnetic nanoparticle, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticle, and a second exchange interaction acting between atoms of the same type in a state where atoms of different types are arranged between them within the magnetic nanoparticle, and setting up a magnetic calculation model; a step of calculating the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; a step of outputting the particle size of the magnetic nanoparticles included in the particle structure information in association with the calculated Curie temperature; An analysis program that executes the above.