Asymmetric Spin-Orbit Torque Wiring for Magnetization Reversal
Solution Overview
Problem
Current spin-orbit torque type magnetization reversal elements require external magnetic fields for magnetization reversal, which limits integration in integrated circuits, and methods like changing oxygen concentration in oxide films are not applicable to all magnetoresistance effect elements, leading to potential data noise and limited general use.
Innovation Solution
A spin-orbit torque type magnetization reversal element with asymmetrical spin injection from spin-orbit torque wiring, where the distance and material composition of the wiring differ along its length, disrupting symmetry and allowing magnetization reversal without an external magnetic field, applicable to both TMR and GMR elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an external magnetic field is used for magnetization reversal, then magnetization reversal can be achieved, but the device complexity increases due to the need for a separate magnetic field generation source
Solution Approach 1:
The patent combines the magnetization reversal function with the existing spin-orbit torque wiring structure by creating asymmetry in the wiring itself. The spin-orbit torque wiring is designed with different widths or cross-sectional areas at different positions along its length, allowing it to generate asymmetric spin injection that directly achieves magnetization reversal without requiring a separate magnetic field generation source. This merging of functions reduces device complexity while maintaining the magnetization reversal capability.
Solution Approach 2:
The patent applies asymmetry to the spin-orbit torque wiring structure by making the wiring have different widths or cross-sectional areas at different positions along its length. This asymmetric geometry creates asymmetric spin injection into the ferromagnetic layer, which generates a net torque for magnetization reversal. The asymmetric structure replaces the need for external magnetic fields while enabling direct control of magnetization orientation through current-induced spin-orbit torque.
2Ease of operation
If oxygen concentration in oxide films is changed to disrupt magnetization symmetry, then magnetization reversal can be achieved, but the adaptability decreases because this method is not applicable to all magnetoresistance effect elements
Solution Approach 1:
The patent applies asymmetry to the spin-orbit torque wiring structure by making the wiring have different widths or cross-sectional areas at different positions along its length. This asymmetric geometry creates asymmetric spin injection into the ferromagnetic layer, which generates a net torque for magnetization reversal. The asymmetric structure replaces the need for external magnetic fields while enabling direct control of magnetization orientation through current-induced spin-orbit torque.
Solution Approach 2:
The patent provides a universal solution for magnetization reversal that applies to both TMR and GMR elements. By using asymmetric spin injection through modified spin-orbit torque wiring, the method works across different magnetoresistance effect element types without requiring material-specific modifications like changing oxygen concentration in oxide films. This universal approach enhances adaptability while maintaining ease of magnetization reversal.
3Stability of the object's composition
If symmetric spin injection is used, then the magnetization symmetry is maintained, but magnetization reversal cannot be achieved without external magnetic fields
Solution Approach 1:
The patent applies asymmetry to the spin-orbit torque wiring structure by making the wiring have different widths or cross-sectional areas at different positions along its length. This asymmetric geometry creates asymmetric spin injection into the ferromagnetic layer, which generates a net torque for magnetization reversal. The asymmetric structure replaces the need for external magnetic fields while enabling direct control of magnetization orientation through current-induced spin-orbit torque.
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
Enables easy magnetization reversal in the absence of a magnetic field, reducing data noise and increasing the versatility of the spin-orbit torque type magnetization reversal element for use in various magnetic memory and high-frequency devices.
Implementation Method 1
much attention has been focused on magnetization reversal that utilizes pure spin current generated by spin-orbit interaction as a technique for reducing the reversal current
Implementation Method 2
Pure spin current generated by spin-orbit interaction induces spin-orbit torque (SOT), with this SOT causing magnetization reversal
Implementation Method 3
Methods for disrupting the magnetization symmetry include a method of applying an external magnetic field and a method of changing the intensity of the magnetic anisotropy in the in-plane direction
Implementation Method 4
giant magnetoresistance (GMR) elements composed of a multilayer film of ferromagnetic layers and non-magnetic layers
Implementation Method 5
tunnel magnetoresistance (TMR) elements which use insulating layers (tunnel barrier layers, barrier layers) for the non-magnetic layers
Data Source
AI summary
A spin-orbit torque type magnetization reversal element including a ferromagnetic metal layer with a varying magnetization direction; and spin-orbit torque wiring that extends in a first direction intersecting with a stacking direction of the ferromagnetic metal layer and that is joined to the ferromagnetic metal layer; wherein when viewed from the first direction, the spin-orbit torque wiring is asymmetrical in a second direction that is orthogonal to the first direction and the stacking direction, with respect to an axis that passes through a center, in the second direction, of the ferromagnetic metal layer.