Enabling high giant magnetoresistance in simple spin valves with ultrathin seed and free layers

TL;DR

This paper demonstrates that adding a 1-nm Cu seed layer in Co-based spin valves maintains high GMR ratios even with ultrathin free layers below 2 nm, advancing spintronic device performance.

Contribution

Introducing a Cu seed layer technique to preserve high GMR signals in ultrathin free layers of spin valves, enabling improved spin-orbit-torque device applications.

Findings

Achieved 5-7% GMR ratios at sub-2-nm free-layer thicknesses.

The Cu seed layer promotes sharp interfaces in polycrystalline Co spin valves.

The method enhances electrical readout signals for spintronic devices.

Abstract

Emerging spin-orbit-torque devices based on spin valves require a thin magnetic free layer to maximize the torque per moment. However, reducing the free-layer thickness to $\lesssim 2$ nm deteriorates the giant magnetoresistance (GMR) signal for electrical readout. Here, we demonstrate that the addition of a 1-nm Cu seed layer promotes sharp interfaces in simple polycrystalline Co-based spin valves, enabling high GMR ratios of 5-7% at sub-2-nm free-layer thicknesses. Our work offers a pathway for engineering high-signal GMR readout in spin-orbit-torque digital memories and neuromorphic computers.