Amorphous Spin-Orbit Torque Wiring for Low Current Magnetic Memory
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Solution Overview
Problem
Magnetic memories with integrated magnetoresistive effect elements face increased power consumption due to high electric current requirements for writing data, necessitating a solution to reduce current usage while maintaining effective data writing.
Innovation Solution
The implementation of a magnetization rotating element utilizing a spin-orbit torque wiring with an amorphous structure, made of oxides, nitrides, or oxynitrides, which allows for efficient spin current generation and reduced reversal current density, enabling data writing with minimal electric current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electric current is applied in the lamination direction of the magnetoresistive effect element to control magnetization direction using spin transfer torque, then the magnetization direction can be controlled, but the electric current causes characteristic deterioration and increases power consumption
Solution Approach 1:
The patent replaces the conventional spin transfer torque method (which requires current flow through the magnetoresistive effect element in the lamination direction) with a spin-orbit torque method (which uses current flow in a planar direction intersecting the lamination direction). This substitution changes the current flow path from penetrating the element structure to flowing along the surface, thereby avoiding the characteristic deterioration caused by lamination-direction current while maintaining magnetization control capability
Solution Approach 2:
The patent introduces a spin-orbit torque wiring as an intermediary component that generates spin current through spin-orbit interaction or Rashba effect at material interfaces. This intermediary mechanism enables magnetization control without requiring direct current flow through the magnetoresistive effect element's lamination direction, thus protecting the element from current-induced deterioration
2Productivity
If the amount of electric current applied to each magnetoresistive effect element is increased to ensure effective data writing, then the data writing effectiveness is improved, but the power consumption of the magnetic memory increases
Solution Approach 1:
The patent changes the critical parameter of current flow direction from lamination direction to planar direction. This parameter change enables the system to achieve effective data writing with lower current magnitude because the spin-orbit torque mechanism is more efficient at generating the necessary spin current for magnetization reversal compared to direct spin transfer torque
Solution Approach 2:
The patent utilizes spin-orbit interaction and Rashba effect as quantum mechanical phase transition phenomena to generate spin current. These quantum effects enable efficient spin current generation at material interfaces, allowing effective data writing with reduced current requirements compared to conventional classical spin transfer torque mechanisms
3Use of energy by moving object
If a spin-orbit torque wiring with amorphous structure made of oxide, nitride, or oxynitride is used to reduce reversal current density, then the electric current requirement is reduced, but the manufacturing precision requirements increase due to oxygen or nitrogen concentration control
Solution Approach 1:
The patent applies local quality by creating different oxygen or nitrogen concentration profiles at different locations within the spin-orbit torque wiring. Specifically, the concentration of oxygen or nitrogen is made different between the first surface (closer to the ferromagnetic layer) and the second surface (opposite surface), with the concentration gradually decreasing from the second surface toward the first surface. This local variation optimizes the spin-orbit torque effect while managing manufacturing complexity
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 approach enables magnetic memories to operate with a small electric current, reducing power consumption while maintaining effective data writing capabilities, thereby extending the lifespan of magnetoresistive effect elements.
Implementation Method 1
An SOT is induced by a spin current caused by spin-orbit interaction or by the Rashba effect at an interface between dissimilar materials
Implementation Method 2
An SOT is induced by a spin current caused by spin-orbit interaction or by the Rashba effect at an interface between dissimilar materials
Implementation Method 3
Giant magnetoresistive (GMR) elements each including a multilayer film of a ferromagnetic layer and a nonmagnetic layer
Implementation Method 4
tunnel magnetoresistive (TMR) elements using an insulation layer (a tunnel barrier layer or a barrier layer) as a nonmagnetic layer
Implementation Method 5
The concentration of oxygen or nitrogen contained in the spin-orbit torque wiring may be lower than a concentration of oxygen or nitrogen of a stoichiometric composition
Data Source
AI summary
This magnetization rotating element includes a spin-orbit torque wiring and a first ferromagnetic layer connected to the spin-orbit torque wiring, wherein the spin-orbit torque wiring has an amorphous structure, and the amorphous structure is made of any of an oxide, a nitride, and an oxynitride.