Diffusion based degradation mechanisms in giant magnetoresistive spin valves

TL;DR

This paper investigates degradation mechanisms in GMR spin valves, identifying oxygen diffusion and interdiffusion as key factors, and demonstrates how selecting appropriate cap layer materials can mitigate oxidation-related degradation.

Contribution

It provides a detailed analysis of degradation pathways in GMR spin valves and proposes material solutions to improve their stability and performance.

Findings

Oxygen diffusion causes oxidation in GMR stacks.

Interdiffusion occurs at functional layers, affecting performance.

Using TaN as a cap layer suppresses oxidation.

Abstract

Spin valve systems based on the giant magnetoresistive (GMR) effect as used for example in hard disks and automotive applications consist of several functional metallic thin film layers. We have identified by secondary ion mass spectrometry (SIMS) two main degradation mechanisms: One is related to oxygen diffusion through a protective cap layer, and the other one is interdiffusion directly at the functional layers of the GMR stack. By choosing a suitable material as cap layer (TaN), the oxidation effect can be suppressed.