Perpendicular magnetic spin valve with nano soft magnetic core

A perpendicular magnetism and spin valve technology, applied in the field of magnetic storage, can solve the problems of high critical inversion current density, influence signal writing, too large difference in critical current size, etc., to improve the difference in critical inversion current size, critical current Density reduction effect

Inactive Publication Date: 2010-10-06
FUDAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the traditional way of writing information with a magnetic field is likely to cause the influence of neighbors. Therefore, in recent years, a new writing method has attracted the attention of researchers, which is to use the spin torque effect generated by the polarization current flowing vertically through the local memory unit. Drive Free Layer Flip
The critical switching current density required by this writing method is too high, which not only consumes high energy, but also is incompatible with other MRAM processes
At the same time, the critical current required for forward and reverse magnetization switching is too different, which will also affect the writing of signals

Method used

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  • Perpendicular magnetic spin valve with nano soft magnetic core
  • Perpendicular magnetic spin valve with nano soft magnetic core
  • Perpendicular magnetic spin valve with nano soft magnetic core

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] This example shows the change of critical switching current density under a group of different soft magnetic core area ratios. As shown in Figure (2), when the area ratio of the soft magnetic core is δ=4.17%, the critical switching current density of the free layer from the parallel state to the antiparallel state is 2.56×10 7 A / cm 2 , which is 44.4% lower than that without soft magnetic core (δ=0%), and the ratio from antiparallel state to parallel state is 0.8×10 7 A / cm 2 , decreased by 18.5%, while the magnetization of the free layer remained basically in the vertical direction (the magnetization in the z direction only decreased by 2%, see figure 2 illustration). With the further increase of the soft magnetic core area ratio δ, the critical current density is further reduced. Considering the stability of the magnetic signal in the vertical direction of the free layer and the reduction of the critical switching current density, the area ratio of the soft magneti...

Embodiment 2

[0026] This example is a group of changes in the switching current pulse time under different soft magnetic core area ratios. Such as image 3 As shown, the spin valve designed in the present invention (the area of ​​the soft magnetic core is 6.3%) is lower than the critical switching current density of the common spin valve with the same parameters, from the parallel state to the antiparallel state critical (P-to-AP) current The inversion time is reduced by 41.2%, and the inversion time from the antiparallel state to the parallel state (AP-to-P) critical current is reduced by 65.1%.

Embodiment 3

[0028] This example shows the effect of the common spin valve and the spin valve of the present invention on improving the symmetry of the critical current of the device. Such as Figure 4 As shown, when δ=0% (ordinary perpendicular anisotropic spin valve), the current density J from the parallel state to the antiparallel state c P-AP , antiparallel state to parallel state current density J c AP-P 4.53×10 7 A / cm 2 and 0.97×10 7 A / cm 2 , whose asymmetry ratio J c P-AP / J c AP-P is 4.67. When δ=12.5%, J c P-AP , J c AP-P 1.98×10 respectively 7 A / cm 2 and 0.89×10 7 A / cm 2 , with an asymmetry ratio of 2.23, a great improvement.

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Abstract

The invention belongs to the technical field of magnetic storage, in particular to a perpendicular magnetic spin valve with a nano soft magnetic core. In the structure of the spin valve, a magnetic reference layer and a free layer respectively adopt a [Co / Pt] multi-layer membrane structure and a [Co / Ni] multi-layer membrane structure with perpendicular magnetic anisotropy. A [NiFeCo] nano soft magnetic core with planar magnetic anisotropy is added in the free layer used for information storage through micro preparation or doping. The area of the nano core can be controlled to be 2-12 percent of the total area of the free layer without influence on signal storage. The micro-magnetic simulation of the nano spin valve device shows that compared with the ordinary perpendicular magnetic spin valve, the magnetization reversal current of the perpendicular magnetic spin valve with the nano core is greatly reduced, the reduction amplitude is up to 56.9 percent, the reversal time is reduced by 65.1 percent, and the strength asymmetry of the critical reversal current is greatly improved simultaneously. Therefore, the invention has significant application value in the research and development of the power-saving, self-spinning, high-capacity and rectangular magnetic random access memory MRAM.

Description

technical field [0001] The invention belongs to the technical field of magnetic storage, and in particular relates to a non-volatile magnetic random access memory (MRAM) and other spin electronic devices, in particular to a perpendicular magnetization spin valve containing in-plane magnetic anisotropy nano soft magnetic core. Background technique [0002] Compared with the in-plane magnetization spin valve, the giant magnetoresistance spin valve or tunnel junction device memory cell with perpendicular magnetic anisotropy has great advantages in MRAM, which not only has no limitation on the aspect ratio of the memory cell , the smaller the size of the memory cell, the less likely the magnetic vortex state at the boundary will appear, which is conducive to the improvement of the recording density, and has good thermal stability. However, the traditional way of writing information with a magnetic field is likely to cause the influence of neighbors. Therefore, in recent years, a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L43/08G11C11/16
CPCG11C11/16
Inventor 张宗芝邱永成李暄马斌金庆原
Owner FUDAN UNIV
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