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

Technical Field

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

Background Art

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

[0003] Generally, the Curie temperature varies according to the particle size of magnetic nanoparticles. Therefore, if there is a large variation in the particle size of magnetic nanoparticles forming the recording layer, the variation in the Curie temperature also becomes large, and the recording quality deteriorates.

[0004] For this reason, it is important to quantitatively indicate the recording quality by measuring in advance the variation in the particle size of magnetic nanoparticles forming the recording layer and managing the range of the Curie temperature of magnetic nanoparticles forming the recording layer.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] While the Curie temperature for each particle size of magnetic nanoparticles can be calculated using magnetic simulation software, conventional magnetic simulation software lacked sufficient calculation accuracy to strictly control the range of the Curie temperature.

[0007] This disclosure improves the calculation accuracy when determining the Curie temperature for each particle size. [Means for solving the problem]

[0008] The information processing device relating to the first aspect of this disclosure is: A setting unit that acquires particle structure information showing the structure of magnetic nanoparticles, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticles, and a second exchange interaction acting between atoms of the same type when different types of atoms are positioned between them within the magnetic nanoparticles, and sets up 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, The system includes an output unit that outputs the particle size of the magnetic nanoparticles included in the particle structure information and the calculated Curie temperature in correspondence.

[0009] A second aspect of this disclosure is an information processing apparatus described in the first aspect, The particle structure information further includes atomic arrangement information that shows the arrangement of atoms contained in the magnetic nanoparticles.

[0010] A third aspect of this disclosure is an information processing apparatus described in the second aspect, The setting unit is, As the first exchange interaction, we obtain the exchange interaction that acts between adjacent atoms in the same plane among the atoms arranged based on the atomic arrangement information. As the second exchange interaction, an exchange interaction is obtained that acts between atoms of the same type in directions perpendicular to the same plane, among the atoms arranged based on the atomic arrangement information.

[0011] A fourth aspect of this disclosure is an information processing apparatus described in the first aspect, When the setting unit sequentially sets up multiple magnetic calculation models in which the particle sizes of the magnetic nanoparticles differ from each other, and the calculation unit sequentially calculates the Curie temperature, the output unit calculates a range of Curie temperatures corresponding to a predetermined range of particle sizes.

[0012] A fifth aspect of this disclosure is an information processing apparatus as described in the fourth aspect, The output unit outputs a graph showing the relationship between the particle sizes of the multiple magnetic nanoparticles and the calculated multiple Curie temperatures.

[0013] A sixth aspect of this disclosure is an information processing apparatus described in the fifth aspect, The output unit superimposes the range of particle size and the range of Curie temperature onto the graph and outputs the result.

[0014] A seventh aspect of this disclosure is an information processing apparatus as described in the fourth aspect, The aforementioned particle size range is determined based on the median particle size and the variance value.

[0015] The eighth aspect of this disclosure is an information processing apparatus described in any of the first to seventh aspects, The magnetic nanoparticles are FePt magnetic nanoparticles.

[0016] A ninth aspect of this disclosure is an information processing apparatus as described in the eighth aspect, 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 positioned between them.

[0017] A tenth aspect of this disclosure is an information processing apparatus described in any of the first to ninth aspects, The first and second exchange interactions are calculated by first-principles calculations.

[0018] The analysis method according to the 11th aspect of the present disclosure is such that a computer acquires particle structure information indicating the structure of magnetic nanoparticles, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticles, and a second exchange interaction acting between atoms of the same type in a state where different types of atoms are arranged therebetween within the magnetic nanoparticles, and sets a magnetic calculation model; calculates the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; and associates and outputs the particle size of the magnetic nanoparticles included in the particle structure information and the calculated Curie temperature.

[0019] The analysis program according to the 12th aspect of the present disclosure causes a computer to acquire particle structure information indicating the structure of magnetic nanoparticles, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticles, and a second exchange interaction acting between atoms of the same type in a state where different types of atoms are arranged therebetween within the magnetic nanoparticles, and sets a magnetic calculation model; to calculate the Curie temperature by calculating the magnetization at each temperature using the set magnetic calculation model; and to associate and output the particle size of the magnetic nanoparticles included in the particle structure information and the calculated Curie temperature.

Advantages of the Invention

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

Brief Description of the Drawings

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

[0022] Each embodiment will be described below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

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

[0024] Reference numeral 140 indicates the positional relationship of various parts around the recording head 133. As shown by reference numeral 140, the recording head 133 has a laser element 141 that irradiates the recording layer 143 with near-field light 142. As a result, the recording layer 143 is heated to the Curie temperature, making it possible to record data at a high recording density in the heat-assisted magnetic recording medium 131. In the first embodiment, the recording layer 143 is formed of FePt magnetic nanoparticles.

[0025] Reference numeral 150 shows a magnified view of the surface of the recording layer 143, where each particle separated by a white line represents an FePt magnetic nanoparticle. The double arrows within reference numeral 150 represent the particle size of one FePt magnetic nanoparticle.

[0026] The analysis system 100 calculates the Curie temperature range of FePt magnetic nanoparticles that form the recording layer 143 of the heat-assisted magnetic recording medium 131 used in the magnetic memory device 130. This allows for a quantitative indication of the recording quality of the recording layer 143.

[0027] Specifically, the measuring device 110 of the analysis system 100 pre-measures the particle size of FePt magnetic nanoparticles that form the recording layer 143 of the heat-assisted magnetic recording medium 131 used in the magnetic memory device 130. The measuring device 110 of the analysis system 100 calculates the median and variance values ​​of the particle sizes as information indicating the variation in the particle sizes measured in the sample, and notifies the information processing device 120.

[0028] The information processing device 120 of the analysis system 100 has an analysis program installed on it, and when this analysis program is executed, 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 the setting information necessary to set up a magnetic calculation model for one FePt magnetic nanoparticle and sets up the magnetic calculation model.

[0030] The Curie temperature calculation unit 122 calculates the Curie temperature by performing magnetic simulation processing using the set magnetic calculation model and calculating the average magnetization of the entire magnetic calculation model at each temperature.

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

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

[0033] Furthermore, if the measuring device 110 has provided information indicating variations in particle size, the output unit 123 calculates the range of particle size based on the information indicating variations in particle size. Subsequently, the output unit 123 calculates the range of Curie temperature corresponding to the range of particle size based on the graph. As a result, the output unit 123 can output the range of particle size and the range of Curie temperature superimposed on the graph.

[0034] <Relationship between temperature and magnetization> Next, we will explain the relationship between magnetization calculated using the magnetic calculation model and temperature. Figure 2A shows the relationship between temperature and magnetization. In Figure 2A, the horizontal axis represents temperature [K] and the vertical axis represents average magnetization [M]. Graph 210 shows the average magnetization at each temperature in the magnetic calculation model.

[0035] Symbol 221 represents the magnetism of each atom in the magnetic calculation model at a temperature of 0[K], symbol 222 represents the magnetism of each atom in the magnetic calculation model at a temperature of 500[K], and symbol 223 represents the magnetism of each atom in the magnetic calculation model at a temperature of 620[K]. The spheres arranged within symbols 221 to 223 each represent a single atom, and dark-colored atoms indicate that the magnetic force is directed in a predetermined unidirectional direction. Light-colored atoms indicate that the magnetic force is directed in multiple directions.

[0036] Figure 2B shows an example of a method for calculating the Curie temperature. In Figure 2B, graph 230 shows the result of fitting the formula described later to graph 210. The Curie temperature calculation unit 122 calculates the Curie temperature by fitting the relationship between temperature and mean magnetization.

[0037] <Overview of the magnetic computation model> Next, we will describe an overview of the magnetic calculation model. First, as a comparative example, we will describe an overview of a magnetic calculation model in which it is difficult to achieve sufficient calculation accuracy using the Curie temperature calculation unit 122. Subsequently, we will describe an overview of a magnetic calculation model in which sufficient calculation accuracy can be achieved using the Curie temperature calculation unit 122.

[0038] Figure 3 is a diagram illustrating the overview of the magnetic calculation model. Of these, Figure 33a shows the process flow up to setting up the magnetic calculation model for the comparative example.

[0039] In Figure 3a, the symbol 310 indicates the arrangement of Fe and Pt atoms in the FePt magnetic nanoparticles. In Figure 3a, the symbol 320 indicates how the arrangement within the FePt magnetic nanoparticles was simplified in order to reduce the computational cost when setting up the magnetic calculation model for the FePt magnetic nanoparticles. Specifically, in the example in Figure 3a, only Fe atoms are arranged on a simple cubic lattice.

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

[0041] In Figure 3, 3a, the symbol 340 indicates that "J" is set as the exchange interaction between adjacent Fe atoms in the configured magnetic calculation model. Regarding conventional magnetic simulation software, for example, the software developer has published a paper listed in the references below. Referring to that paper, it is stated that for the magnetic calculation model of FePt magnetic nanoparticles, only one value is set as the exchange interaction between atoms. Therefore, according to that paper, as shown by symbol 340, in the case of the comparative example's magnetic calculation model, only one value is set as the exchange interaction 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> Note that, due to space limitations, the example for symbol 340 is as follows: • Of the Fe atoms included in the magnetic calculation model, only the Fe atom indicated by symbol 341 and the Fe atoms adjacent to the Fe atom indicated by symbol 341 (symbols 342 to 347) are shown. • As an exchange interaction, only the exchange interaction between the Fe atom indicated by symbol 341 and the Fe atoms adjacent to it (symbols 342 to 347) is shown.

[0043] However, for Fe atoms other than the Fe atom indicated by symbol 341, "J" is assumed to be set as the exchange interaction acting between them and adjacent Fe atoms, similar to the example of symbol 340.

[0044] In contrast, Figure 3b shows the process of setting up a magnetic calculation model that can achieve sufficient calculation accuracy using the Curie temperature calculation unit 122.

[0045] In Figure 3, 3b, reference numerals 310 to 330 are the same as reference numerals 310 to 330 in Figure 3, 3a, so their explanation is 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 Figure 3, 3b, reference numeral 350 denotes the magnetic calculation model, • We define "J'" as the first exchange interaction acting between adjacent Fe atoms (symbols 342-345) within the same plane 351. "J" was defined as the second exchange interaction between Fe atoms (symbols 346 and 347) arranged in adjacent positions in directions perpendicular to the same plane 351. This illustrates the situation. However, it is assumed that the relationship is "J'" > "J"". The reason for assuming "J'" > "J" is that, in setting up the magnetic calculation model, a configuration was chosen in which only Fe atoms were arranged for simplification, but in reality, a Pt atom is placed between the Fe atom indicated by symbol 341 and the Fe atom indicated by symbol 346. In other words, the exchange interaction acting between Fe atoms (symbols 346, 347) with a Pt atom, which is a different type of atom, placed in between is smaller than the exchange interaction acting between Fe atoms (symbols 342 to 345) without a Pt atom placed in between.

[0048] Thus, the information processing device 120 according to the first embodiment sets up a magnetic calculation model, • By arranging only Fe atoms on a simple cubic lattice, computational costs are reduced, By differentiating the exchange interaction between atoms of the same type (between Fe atoms) depending on whether they are in the same plane 351 or perpendicular to the same plane 351, an effect similar to that of arranging Pt atoms can be achieved. This configuration allows for improved calculation accuracy in the calculation of the Curie temperature, according to the information processing device 120 of the first embodiment.

[0049] <Hardware configuration of the information processing device> Next, the hardware configuration of the information processing device 120 will be described. Figure 4 shows an example of the hardware configuration of the information processing device. As shown in Figure 4, the information processing device 120 includes a processor 401, memory 402, auxiliary storage device 403, I / F (Interface) device 404, communication device 405, and drive device 406. The hardware components of the information processing device 120 are interconnected via a bus 407.

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

[0051] Memory 402 has main memory devices such as ROM (Read Only Memory) and RAM (Random Access Memory). The processor 401 and memory 402 form a so-called computer, and the computer realizes various functions by the processor 401 executing various programs read into memory 402.

[0052] The auxiliary storage device 403 stores various programs and various data used when those programs are executed by the processor 401. For example, the data storage unit 535, which will be described later, is implemented in the auxiliary storage device 403.

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

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

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

[0056] <Functional Configuration of Information Processing Devices> Next, we will describe the details of the functional configuration of the information processing device 120. Figure 5 is a diagram showing an example of the functional configuration of the information processing device.

[0057] As shown in Figure 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 the magnetic calculation model for one FePt magnetic nanoparticle to be simulated. 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 Figure 3 and performs magnetic simulation processing. For this reason, the particle structure information acquisition unit 511, for example, • Atomic arrangement information: On a simple cubic lattice, with interatomic distance L, only Fe atoms are arranged in N 2 array • Particle size and shape: Cube shape with sides of (N-1) × L Obtain it.

[0060] The exchange interaction information acquisition unit 512 acquires the first exchange interaction and the second exchange interaction from the above setting information. As explained in Figure 3b, 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 it in the Curie temperature calculation unit 122.

[0062] As shown in Figure 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 added 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 (direction of the magnetic moment of each atom, 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, that is, 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 determination unit 524 calculates the Curie temperature by fitting the average magnetization and temperature plots using the following equation 1.

[0067]

number

[0068] As shown in Figure 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] The Curie temperature acquisition unit 531 acquires the Curie temperature from the Curie temperature calculation unit 122 when the Curie temperature calculation unit 122 completes the magnetic simulation processing, and stores it in the data storage unit 535. The Curie temperature acquisition unit 531 acquires the Curie temperature for multiple magnetic calculation models 522 with different particle sizes as targets for magnetic simulation, and stores them in the data storage unit 535 as stored 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 in the data storage unit 535 as stored data. The particle size acquisition unit 532 sequentially acquires the particle sizes of multiple magnetic calculation models 522, each with different particle sizes, during the magnetic simulation process. Each time the Curie temperature is acquired by the Curie temperature acquisition unit 531, the particle size acquisition unit 532 associates the sequentially acquired particle size with the acquired Curie temperature and stores it in the data storage unit 535 as stored data.

[0071] The temperature range calculation unit 533 calculates the particle size range based on information indicating particle size variation notified from the measuring device 110. Specifically, the temperature range calculation unit 533 calculates the particle size range using the median and variance values ​​included in the information indicating particle size variation. 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 multiple combinations of Curie temperature and particle size stored in the data storage unit 535. The range of Curie temperatures calculated by the temperature range calculation unit 533 includes: • Curie temperature corresponding to the median particle size • Curie temperature corresponding to median-variance of particle size / 2 • Curie temperature corresponding to median particle size + variance / 2 This includes the following. The temperature range calculation unit 533 notifies the graphing unit 534 of the range of particle size and the range of Curie temperature.

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

[0074] <Flowchart for calculating the Curie temperature range> Next, we will explain the process for calculating the Curie temperature range using the analysis system 100. Figure 6 is the first flowchart showing the process for calculating the Curie temperature range.

[0075] In step S601, the measuring device 110 measures the particle size of FePt magnetic nanoparticles applied to the target equipment 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 obtains the first and second exchange interactions of FePt magnetic nanoparticles by receiving input of the first and second exchange interactions of FePt magnetic nanoparticles from the user.

[0077] In step S603, the information processing device 120 obtains from the user particle structure information for a magnetic calculation model of one FePt magnetic nanoparticle, including atomic arrangement information, particle size, particle shape, etc.

[0078] In step S604, the information processing device 120, The first exchange interaction and the second exchange interaction obtained in step S602, • Particle structure information obtained in step S603, A magnetic calculation model is set up for one FePt magnetic nanoparticle, which is identified based on the configuration information including the above.

[0079] In step S605, the information processing device 120 performs magnetic simulation processing using the configured 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 perform magnetic simulation processing for other particle sizes. If it is determined in step S607 to perform magnetic simulation processing for other particle sizes (i.e., the answer in step S607 is YES), the process returns to step S603. In this case, in step S603, the information processing device 120 obtains particle structure information including other particle sizes and sequentially sets up multiple magnetic calculation models with different particle sizes, thereby executing the processes in steps S604 to S607. As a result, the information processing device 120 can sequentially calculate the Curie temperature corresponding to each particle size.

[0082] On the other hand, if it is determined in step S607 that magnetic simulation processing should not be performed for other particle sizes (i.e., the answer in step S607 is NO), 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 in steps S603 to S607 and obtains multiple combinations of particle size and Curie temperature generated by performing magnetic simulation processing for different particle sizes. Based on the multiple combinations of particle size and Curie temperature obtained, the information processing device 120 generates a graph. The information processing device 120 superimposes the range of particle size calculated in step S601 and the range of Curie temperature calculated in step S608 onto the generated graph and outputs it.

[0085] <Examples of stored data> Next, we will describe a specific example of the data stored in the data storage unit 535. Figure 7 shows an example of the stored data.

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

[0087] <Examples of graphs> Next, a specific example of a graph generated by the graphing unit 534 will be described. Figure 8 shows a graph illustrating the relationship between particle size and Curie temperature, with the range of particle size and the range of Curie temperature superimposed on it.

[0088] In Graph 800 shown in Figure 8, the horizontal axis represents particle size [nm] and the vertical axis represents Curie temperature [K]. In Graph 800, the symbol 801 represents the median particle size of FePt magnetic nanoparticles measured by the measuring device 110. In Graph 800, the symbol 802 represents the particle size obtained by adding or subtracting half of the dispersion value δD of the FePt magnetic nanoparticle size measured by the measuring device 110 to the median.

[0089] In graph 800, the symbol 811 represents the Curie temperature at the intersection of the straight line symbol 801, which represents the median particle size, and the curve 820, which represents the Curie temperature. In graph 800, the symbol 812 represents the Curie temperature at the intersection of the straight line symbol 802, which represents the particle size obtained by adding or subtracting half of the dispersion value δD of the particle size to the median, and the curve 820, which represents the Curie temperature.

[0090] In other words, the range enclosed by the line labeled 802 represents the range of particle sizes, and the range enclosed by the line labeled 812 represents the range of Curie temperatures.

[0091] <Explanation of calculation accuracy> Next, we will explain the differences in the accuracy of the Curie temperature calculation due to the differences in the magnetic calculation models used. Figure 9A is the first figure showing the differences in calculation accuracy due to the differences in the magnetic calculation models. In the graph 900 shown in Figure 9A, the horizontal axis represents particle size [nm] and the vertical axis represents the Curie temperature [K].

[0092] In graph 800, symbols 901 and 902 are, • Magnetic calculation model for a simple cubic lattice, • Magnetic calculation models where the Curie temperature is 750 K in all cases, assuming a particle size of 12 nm. This figure shows how magnetic simulation processing was performed using the method described above to calculate the Curie temperature for each particle size. However, the symbol 901 indicates the case where magnetic simulation processing was performed using a magnetic calculation model in which "J" is set as the exchange interaction between adjacent Fe atoms (comparative example), as shown in 3a of Figure 3. On the other hand, the symbol 902 indicates the case where magnetic simulation processing 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 (this method), as shown in 3b of Figure 3.

[0093] Comparing symbols 901 and 902, the decrease in Curie temperature is greater for symbol 902 and smaller for symbol 901 as the particle size decreases. Furthermore, experimental values ​​of Curie temperature at each particle size show a greater decrease in Curie temperature as the particle size decreases, resulting in values ​​close to those of symbol 902.

[0094] Figure 9B is a second figure showing the difference in calculation accuracy due to differences in magnetic calculation models. The Curie temperature calculated from the average magnetization measured when FePt magnetic nanoparticles were actually heated, The Curie temperature calculated from the average magnetization obtained by performing a magnetic simulation using a magnetic calculation model that reproduces the FePt magnetic nanoparticles, This is a comparison of the two.

[0095] In Figure 9B, under reference numeral 910, "Summary of particle size of FePt magnetic nanoparticles used in the experiment" refers to the summation of particle sizes in the planar and cross-sectional directions obtained by analyzing the FePt magnetic nanoparticles used in the experiment using a TEM. TEM is an abbreviation for Transmission Electron Microscope.

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

[0097] On the other hand, in Figure 9B, the symbol 911 shows an overview of the Curie temperature when magnetic simulation processing is performed using a magnetic calculation model in which "J" is set as the exchange interaction between adjacent Fe atoms (comparative example).

[0098] Furthermore, the symbol 912 in Figure 9B shows an overview of the Curie temperature when magnetic simulation processing is 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 (this method).

[0099] Comparing symbols 911 and 912, the variance of the Curie temperature in symbol 911 is outside the variance of the Curie temperature in symbol 910, whereas the variance of the Curie temperature in symbol 912 is included in the variance of the Curie temperature in symbol 910.

[0100] Thus, • When using a magnetic calculation model in which "J'" is set as the first exchange interaction and "J"" is set as the second exchange interaction, • When using a magnetic calculation model in which "J" is set as the exchange interaction, Comparing the two methods, Figures 9A and 9B verify that the former method yields higher calculation accuracy in determining the Curie temperature.

[0101] <Summary> As is clear from the above description, the information processing apparatus 120 according to the first embodiment is This process obtains particle structure information showing the structure of FePt magnetic nanoparticles, the first exchange interaction acting between Fe atoms contained in the FePt magnetic nanoparticles, and the second exchange interaction acting between Fe atoms when Pt is positioned between them within the FePt magnetic nanoparticles. • The acquired particle structure information, along with the first and second exchange interactions, is used to set up a magnetic calculation model. The Curie temperature is calculated by performing a magnetic simulation using the configured magnetic calculation model and calculating the average magnetization at each temperature. • Generate and output a graph showing the relationship between the particle size of magnetic nanoparticles included in the particle structure information and the calculated Curie temperature.

[0102] Thus, by performing magnetic simulation processing using a magnetic calculation model in which the first and second exchange interactions are set, it is possible to calculate the Curie temperature with high calculation accuracy. In other words, according to the first embodiment, the calculation accuracy can be improved when calculating the Curie temperature for each particle size.

[0103] [Second Embodiment] In the first embodiment described above, the calculation method for the first exchange interaction "J'" and the second exchange interaction "J''" was not mentioned, but the first and second exchange interactions may be calculated by first-principles calculations. Below, the second embodiment will be described, focusing on the differences from the first embodiment.

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

[0105] The information processing device 1010 has a first-principles calculation program installed, and when this program is executed, the information processing device 1010 functions as a first-principles calculation unit 1011.

[0106] The first-principles calculation unit 1011 receives information about the FePt magnetic particle crystal. This allows the first-principles calculation unit 1011 to calculate the first and second exchange interactions of the FePt magnetic nanoparticles using first-principles calculations.

[0107] For example, the first-principles calculation unit 1011 calculates the first exchange interaction as J' = 9.54 × 10 -21 [J / link] is defined as the second exchange interaction, and 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] <Flowchart for calculating the Curie temperature range> Next, the flow of the Curie temperature range calculation process by the analysis system 1000 will be described. Figure 11 is a second flowchart showing the flow of the Curie temperature range calculation process. The difference from the flowchart described using Figure 5 in the first embodiment above is in steps S1101 to S1103.

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

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

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

[0113] <Summary> As is clear from the above description, the information processing device 120 according to the second embodiment is • It has the same functions as the information processing device 120 according to the first embodiment. When obtaining the first and second exchange interactions, the first and second exchange interactions are obtained by first-principles calculations using the information processing device 1010.

[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 calculates the Curie temperature each time the user changes the particle size. However, the method of setting the particle size is not limited to this, and for example, multiple particle sizes may be set together as the particle size of the magnetic calculation model to be simulated. In this case, the Curie temperature calculation unit 122 may be configured to sequentially calculate the Curie temperature for the set multiple particle sizes.

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

[0117] Furthermore, in each of the above embodiments, the information processing device 120 was described as outputting a range of Curie temperatures for the purpose of quantitatively indicating 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 optimal particle shape for FePt magnetic nanoparticles may be searched for by changing the particle shape included in the setting information and calculating the range of Curie temperatures for each particle shape. The particle shapes referred to here include, for example, rectangular prisms, cylinders, and hexagonal prisms.

[0119] Alternatively, it may be used to search for the optimal magnetic nanoparticle by inputting setting information to specify magnetic nanoparticles other than FePt magnetic nanoparticles and calculating the Curie temperature range for each type of magnetic nanoparticle.

[0120] Furthermore, in the second embodiment described above, the information processing device 1010 and the information processing device 120 were configured as separate components, but the information processing device 1010 and the information processing device 120 may be configured as a single unit.

[0121] It should be noted that the present invention is not limited to the configurations shown in the above embodiments, including combinations with other elements. These aspects can be modified without departing from the spirit of the present invention and can be appropriately determined according to their application.

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

[0123] 100: Analysis System 110: Measuring device 120: Information Processing Device 121: Settings section 122: Curie temperature calculation unit 123: Output section 511: Particle structure information acquisition section 512: Exchange interaction information acquisition unit 513: Magnetic calculation model setting section 521: Temperature Control Unit 522: Magnetic Calculation Model 523: Average magnetization calculation section 531: Curie temperature acquisition unit 532: Particle size acquisition unit 533: Temperature range calculation unit 534: Graphing section 800: Graph 1010: Information Processing Device 1011: First-principles calculation department

Claims

1. A setting unit that acquires particle structure information showing the structure of magnetic nanoparticles, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticles, and a second exchange interaction acting between atoms of the same type when different types of atoms are positioned between them within the magnetic nanoparticles, and sets up 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 and the calculated Curie temperature in correspondence. An information processing device having

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

3. The setting unit is, As the first exchange interaction, we obtain the exchange interaction that acts between adjacent atoms in the same plane among the atoms arranged based on the atomic arrangement information, The information processing apparatus according to claim 2, wherein, as the second exchange interaction, an exchange interaction acting between atoms of the same type in directions perpendicular to the coplane among the atoms arranged based on the atomic arrangement information is obtained.

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

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

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

7. The information processing apparatus according to claim 4, wherein the range of particle sizes is determined based on the median particle size and the variance value.

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

9. The information processing apparatus 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 a Pt atom positioned between them.

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

11. Computers A process of obtaining particle structure information showing the structure of magnetic nanoparticles, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticles, and a second exchange interaction acting between atoms of the same type when different types of atoms are positioned between them within the magnetic nanoparticles, and setting up a magnetic calculation model. The process 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 and the calculated Curie temperature in correspondence. An analysis method to perform this task.

12. On the computer, A process of obtaining particle structure information showing the structure of magnetic nanoparticles, a first exchange interaction acting between adjacent atoms of the same type within the magnetic nanoparticles, and a second exchange interaction acting between atoms of the same type when different types of atoms are positioned between them within the magnetic nanoparticles, and setting up a magnetic calculation model. The process 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 and the calculated Curie temperature in correspondence. An analysis program that executes the necessary steps.

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