Spin-orbit-torque element with oxide interlayer for fast magnetization reversal

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Solution Overview

Problem

The mechanism for magnetization reversal in spin-orbit-torque magnetization rotational elements is not well understood, leading to challenges in quickly performing magnetization reversal, which can result in unreliable data writing and reduced device reliability due to low damping constants in ferromagnetic layers.

Innovation Solution

Incorporating an oxide containing layer between ferromagnetic layers in a spin-orbit-torque magnetization rotational element, where the oxide layer contains non-magnetic elements like Al, Si, or heavy metals, and has insufficient oxygen, to increase the damping constant and facilitate faster magnetization reversal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the damping constant of the ferromagnetic layer is decreased to enable magnetization reversal using spin transfer torque, then energy consumption is reduced and integration is improved, but erroneous writing may occur during reading and device reliability is lowered

Engineering Contradiction:

Improveenergy consumptionVSAvoiddevice reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The invention changes the damping constant parameter by introducing an oxide containing layer with specific properties (contains oxide of non-magnetic element, insufficient oxygen relative to stoichiometric composition) between the ferromagnetic layer and tunnel barrier layer. This allows the damping constant to be optimized for reliable operation while maintaining low energy consumption for magnetization reversal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite structure consisting of a ferromagnetic layer combined with an oxide containing layer (made of non-magnetic elements such as Al, Si, Mg, Ti, Cr, Cu, Mo, Ru, Rh, Pd, Hf, Ta, W, Re, Ir, Pt, or Bi). This composite structure achieves both low energy consumption and high reliability by controlling the damping constant through the oxide layer's presence.

Inventive Principle:

Principle #40Composite materials

2Power

If the damping constant of the ferromagnetic layer is decreased to facilitate magnetization reversal, then the critical writing current density is reduced, but the magnetic anisotropic energy also decreases making the magnetization more easily reversed and read

Engineering Contradiction:

Improvecritical writing current densityVSAvoidreading reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The oxide containing layer modifies the damping constant parameter to achieve an optimal balance: low enough to enable efficient magnetization reversal with acceptable current density, but high enough to provide sufficient magnetic anisotropic energy to prevent erroneous reading. The layer's composition (oxide of non-magnetic element with insufficient oxygen) is specifically designed to achieve this parameter optimization.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If a ferromagnetic layer with low damping constant is used to achieve energy saving and high integration, then the magnetization can be reversed more easily, but the device reliability is compromised due to potential erroneous writing

Engineering Contradiction:

Improveintegration densityVSAvoiddevice reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention employs a composite structure of ferromagnetic layer plus oxide containing layer to achieve both high integration density and high reliability. The oxide layer (containing oxide of non-magnetic element with insufficient oxygen) enables the use of thin ferromagnetic layers for high integration while maintaining adequate damping constant for reliable operation.

Inventive Principle:

Principle #40Composite materials

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 allows for quick magnetization reversal of the ferromagnetic layers, enhancing the reliability and efficiency of data writing in magnetic memory devices by increasing the damping constant and stabilizing the magnetization against thermal disturbances.

Implementation Method 1

The damping constant is a physical quantity generated from spin-orbit interaction. For that reason, the damping constant has a close relationship with the magnetic anisotropic energy.

Methodology Applied

Scientific EffectSpin-orbit interaction:

Implementation Method 2

magnetization reversal using a pure spin current generated by spin-orbit interaction has been gaining attention as means for reducing a reversal current (for example, Non-Patent Document 2). The pure spin current generated by the spin-orbit interaction causes a spin-orbit-torque (SOT).

Methodology Applied

Scientific EffectSpin-orbit-torque:

Data Source

PatentUS11391794B2Spin-orbit-torque magnetization rotational element, spin-orbit-torque type magnetoresistance effect element, and magnetic memory

Publication Date: 2022.07.19 TDK CORP

AI summary

A spin-orbit-torque magnetization rotational element includes: a spin-orbit-torque wiring; and a laminated body laminated on the spin-orbit-torque wiring, wherein the laminated body includes a first ferromagnetic layer, an oxide containing layer, and a second ferromagnetic layer in order from the spin-orbit-torque wiring, wherein the oxide containing layer contains an oxide of a non-magnetic element, and wherein the first ferromagnetic layer and the second ferromagnetic layer are ferromagnetically coupled to each other.