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Spin transfer torque magnetic memory device using magnetic resonance precession and the spin filtering effect

Inactive Publication Date: 2014-06-12
SAMSUNG ELECTRONICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The new magnetic memory device structure improves performance by using a fixed saturation magnetization value for a horizontal direction variable magnetization layer, reducing switching current and power consumption. It also prevents stray field effects and ensures thermal stability of written magnetization data.

Problems solved by technology

If an external magnetic field is used in order to control the magnetization of a free layer, a half-selected cell problem occurs with the reduction of a size of a device to limit high integration of the device.
This is a limitation of super-paramagnetism and causes a problem that a written magnetic data is undesirably erased.
In addition, because the amount of a current provided in a complementary metal-oxide-semiconductor (CMOS) transistor device is limited, a low critical current density for the magnetization reversal of the free magnetic layer is required.
However, the principle and the structure surely require an additional device for inducing the modulation magnetic field, and it was confirmed that a reduction effect of a driving power was less effective in an entire device.
Thus, characteristics of the device are deteriorated by the stray field generated from the first magnetic material.
Additionally, if the saturation magnetization value of a magnetic layer is 650 emu / cm3 or more, the influence of a corresponding magnetic layer on a neighboring magnetic layer increases to be likely to cause problems on characteristics of the device.

Method used

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  • Spin transfer torque magnetic memory device using magnetic resonance precession and the spin filtering effect
  • Spin transfer torque magnetic memory device using magnetic resonance precession and the spin filtering effect
  • Spin transfer torque magnetic memory device using magnetic resonance precession and the spin filtering effect

Examples

Experimental program
Comparison scheme
Effect test

embodiment

[0073]The effect of the magnetic memory device according to the present invention was confirmed through micro-magnetic modeling using an equation of motion of magnetization. The justification of this method was efficiently secured through a conventional computer hard disk development and spin-transfer-torque research.

[0074]The equation of motion of the magnetization is expressed by the following equation 3.

∂m1∂f=-γ(m1×H2eff)+αm1×∂m1∂t-γℏη1je2eMS1d1m1×(m1×p1)+γℏjeη2→12eMS1d1m1×(m1×m2)∂m2∂f=-γ(m2×H2eff)+αm2×∂m2∂t-γℏη2je2eMSd2m2×(m2×m1)+γℏη3je2eMS2d2m1×(m1×p2)p1=z^,p2=-z^[Equation3]

[0075]In the equation 3,

[0076]“m1” and “m2” denote unit magnetization vectors of the first free magnetic layer 203 and 303 and the second free magnetic layer 205 and 305, respectively, “γ” denotes a magnetic rotational constant, “H1eff” and “H2eff” denotes entire effective magnetic field vectors of the first free magnetic layer 203 and 303 and the second free magnetic layer 205 and 305, respectively, “α” den...

experimental example 1

Magnetization Behavior of First Free Magnetic Layer and Second Free Magnetic Layer According to a Time Caused by Applying a Current to the Device According to the Present Invention

[0077](1) There is illustrated magnetization behavior of the first free magnetic layer having the perpendicular anisotropy and the second free magnetic layer having the horizontal anisotropy when the current is applied to the magnetic memory device according to an embodiment of the present invention as shown in the following FIG. 2.

[0078](2) Structure and physical property values of the device are as follows:

[0079]sectional area of an entire structure=314 nm2,

[0080]fixed magnetic layer 201 / first non-magnetic layer 202 / first free magnetic layer 203: “thickness (t)=3 nm, perpendicular anisotropy constant (K⊥)=6×106 erg / cm3, saturation magnetization value (MS1)=1000 emu / cm3, Gilbert damping constant (α)=0.01, and spin polarization efficiency constant (η1)=1.0”,

[0081]second non-magnetic layer 204: thickness t=...

experimental example 2

Measurement of Switching Probabilities with Respect to Currents Applied to a Device According to the Present Invention and a Device According to a Conventional Structure

[0091](1) There are illustrated switching currents with respect to the conventional structure of FIG. 1 and the new structure according to the present invention of FIG. 2.

[0092](2) Structure and physical property values of the devices are as follows.

[0093]A sectional area of an entire structure of each of the two structures is 314 nm2.

[0094]The conventional structure of FIG. 1 has fixed magnetic layer 101 / non-magnetic layer 102 / free magnetic layer 103: “thickness (t)=3 nm, perpendicular anisotropy constant (K⊥)=6×106 erg / cm3, saturation magnetization value (MS1)=1000 emu / cm3, Gilbert damping constant (α)=0.01, and spin polarization efficiency constant (η1)=1.0”.

[0095]The physical property values of the new structure according to the present invention are as follows:

[0096]fixed magnetic layer 201 / first non-magnetic la...

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Abstract

The present invention relates to a magnetic memory device which additionally comprises a free magnetic layer constituting a horizontal direction variable magnetization layer having a fixed saturation magnetization value, whereby a switching current is markedly reduced as compared with conventional magnetic layers such that a high degree of integration of the device can be achieved and it is possible to lower a critical current density necessary for magnetization reversal thereby reducing the power consumption of the device. Also, a stray field effect occurring from a fixed magnetic layer is reduced such that a written magnetization data is thermally stable.

Description

TECHNICAL FIELD[0001]The present invention relates to a magnetic memory device, and more particularly, to a spin transfer torque magnetic device that induces an alternating current magnetic field in itself in the injection of a current by inserting a free magnetic layer having horizontal anisotropy into a free layer having perpendicular anisotropy and that includes two fixed magnetic layers having magnetization directions opposite to each other not to deteriorate its characteristics by a stray field occurring from a fixed magnetic layer.BACKGROUND ART[0002]A ferromagnetic material means a material that is spontaneously magnetized even though a strong magnetic field is not applied from the outside. A giant magnetic resistance effect that an electric resistance is changed depending on relative magnetization directions of two magnetic layers occurs in a spin valve structure having a non-magnetic material inserted between two ferromagnetic bodies (a first magnetic material / a non-magneti...

Claims

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Application Information

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IPC IPC(8): H01L43/02
CPCH01L43/02G11C11/16G11C11/161H10N50/10H10N50/80H10N50/85
Inventor LEE, KYUNG-JINSEO, SOO-MAN
Owner SAMSUNG ELECTRONICS CO LTD
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