Spin Current Magnetoresistance Element with Segmented Recording Layer
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Solution Overview
Problem
Current magnetoresistance effect elements face challenges in achieving high writing efficiency through magnetization reversal using spin-orbit torque (SOT) without an external magnetic field, as the direction of the axis of easy magnetization in recording layers is not sufficiently non-uniform, leading to inefficient magnetization reversal and a decrease in MR ratio.
Innovation Solution
A spin current magnetoresistance effect element is designed with a specific configuration where the end portions of layers are positioned to create three regions with different axes of easy magnetization in the second ferromagnetic metal layer, allowing for magnetization reversal using spin transfer torque and spin-orbit torque without an external magnetic field, while minimizing the decrease in MR ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the end portions of layers are positioned to create three regions with different axes of easy magnetization in the second ferromagnetic metal layer, then writing efficiency is enhanced and magnetization reversal is facilitated, but the device structure becomes more complex
Solution Approach 1:
The second ferromagnetic metal layer is segmented into three distinct regions with different axes of easy magnetization by positioning the end portions of the first ferromagnetic metal layer, non-magnetic layer, and spin-orbit torque wiring at different locations. This segmentation enables independent magnetization reversal in each region, improving writing efficiency without requiring external magnetic fields.
Solution Approach 2:
Different regions within the second ferromagnetic metal layer are assigned different local magnetic properties (different axes of easy magnetization) to optimize their individual responses to spin-orbit torque. The first region has in-plane easy magnetization, while the second and third regions have perpendicular easy magnetization, allowing each region to be reversed efficiently by the SOT wiring.
2Device complexity
If magnetization reversal is performed using spin-orbit torque without an external magnetic field, then the degree of integration is improved and no additional magnetic field generation source is needed, but the axis of easy magnetization must be non-uniform which is difficult to achieve sufficiently
Solution Approach 1:
Instead of attempting to create a continuously non-uniform axis of easy magnetization throughout the recording layer, the invention segments the layer into three discrete regions with clearly defined different magnetization axes. This segmentation approach achieves the necessary non-uniformity more readily than a continuous gradient would.
Solution Approach 2:
The structure introduces asymmetry by positioning the end portions of different layers at different locations, creating three regions with inherently different magnetic anisotropy characteristics. This asymmetric configuration naturally produces the non-uniform axes of easy magnetization required for efficient SOT-based reversal without external fields.
3Productivity
If the third end portion of the non-magnetic layer is located between the first end portion of the first ferromagnetic metal layer and the second end portion of the second ferromagnetic metal layer, then magnetization reversal efficiency is improved, but the control of magnetization direction becomes more difficult
Solution Approach 1:
The magnetization reversal process is segmented into regional operations, where each of the three regions can be reversed independently or collectively. The specific positioning of the third end portion enables the spin-orbit torque wiring to effectively influence all three regions, improving overall reversal efficiency while maintaining controllable magnetization directions through material selection and geometric configuration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances writing efficiency by facilitating easy magnetization reversal in the second ferromagnetic metal layer, achieving high-speed magnetization reversal without an external magnetic field and maintaining a high MR ratio.
Implementation Method 1
a spin-orbit torque wiring 20 extending in a first direction x which intersects a lamination direction z of the magnetoresistance effect element 10 and joined to the second ferromagnetic metal layer 2
Implementation Method 2
tunneling magnetoresistance (TMR) elements using insulating layers (tunnel barrier layers or barrier layers) as non-magnetic layers are known as magnetoresistance effect elements
Data Source
AI summary
Provided is a spin current magnetoresistance effect element, including: a magnetoresistance effect element including a first ferromagnetic metal layer, a second ferromagnetic metal layer configured for magnetization direction to be changed, and a non-magnetic layer sandwiched between the first ferromagnetic metal layer and the second ferromagnetic metal layer; and a spin-orbit torque wiring extending in a first direction which intersects a lamination direction of the magnetoresistance effect element and joined to the second ferromagnetic metal layer, wherein, a third end portion of the non-magnetic layer is located between a first end portion of the first ferromagnetic metal layer and a second end portion of the second ferromagnetic metal layer as viewed from the lamination direction on one of side surfaces of the magnetoresistance effect element.