Oxidation-Resistant Cap Layers for High-Temperature Spintronic Stacks

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Solution Overview

Problem

Spintronic devices utilizing YPtBi and BiSb materials face oxidation issues at higher temperatures, leading to breakdown and operational limitations.

Innovation Solution

Incorporation of a high oxidation resistive cap layer made from materials like IrxHfyAlz, ZrQX, or SixAl1-xN, which provide high resistance, lower roughness, and higher oxidation resistance, allowing operation up to 900°C.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If YPtBi and BiSb materials are used in spintronic devices, then high spin Hall angles and good thermal robustness are achieved, but oxidation occurs at temperatures greater than 300°C leading to breakdown

Engineering Contradiction:

Improveoperating temperatureVSAvoidoxidation resistance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

A cap layer comprising WxMo1-xO3, WxRu1-xO3, WxIr1-xO3, or WxPt1-xO3 is introduced as an intermediary protective barrier between the topological material layer (YPtBi or BiSb) and the oxidizing environment. This cap layer has high oxidation resistance and serves as a mediator that prevents oxygen from reaching and oxidizing the sensitive topological material, thereby enabling operation at temperatures above 300°C without breakdown

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The spintronic device structure is designed as a composite material system combining the topological material layer (YPtBi or BiSb) with a protective cap layer (WxMo1-xO3, WxRu1-xO3, WxIr1-xO3, or WxPt1-xO3). This composite structure leverages the high spin Hall angle and thermal robustness of the topological material while adding the oxidation resistance of the cap layer, achieving both high-temperature operation and oxidation protection

Inventive Principle:

Principle #40Composite materials

2Temperature

If higher operating temperatures are pursued, then thermal robustness is improved, but oxidation and breakdown occur

Engineering Contradiction:

Improveoperating temperatureVSAvoidmaterial stability

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The cap layer (WxMo1-xO3, WxRu1-xO3, WxIr1-xO3, or WxPt1-xO3) acts as a thermal-stable intermediary layer that maintains material stability at high temperatures. It has both high oxidation resistance and thermal stability, serving as a protective barrier that prevents the topological material from oxidizing and decomposing even when operated at temperatures significantly above 300°C, thus maintaining composition stability under thermal stress

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20260066170A1High Oxidation Resistive Cap Layers For Topological Semi-metal and Insulator Materials

Publication Date: 2026.03.05 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

The present disclosure generally relates to spintronic devices comprising a high oxidation resistive cap layer. The spintronic stack comprises a buffer layer, a topological material (TM) layer comprising YPtBi or BiSb, an interlayer, a ferromagnetic layer, and a cap layer. The cap layer comprises a high resistance material selected from the group consisting of: (1) IrxHfyAlz or IrxZryAlz, where x is between about 40 at. % to about 90 at. %, y is about 0.5 at. % to about 60 at. %, and z is about 0.5 at. % to about 60 at. %; (2) ZrQX or HfQX, where X and Q are each individually selected from the group consisting of: Ru, Co, Cu, Ir, Pt, Ti, Nb, Ni, RuAl, Zr, Hf, and CoFe; (3) SixAl1-xN, TixAl1-xN, CrxAl1-xN, and ZrxAl1-xN, where x is a numeral between 0.005 and 1; and (4) nitrides of Si, Al, Ti, Cr, and Zr.