Stress in Spin-Valve Nanopillars due to Spin Transfer

TL;DR

This paper investigates how spin transfer in spin-valve nanopillars induces mechanical stress, revealing that the stress is minimal and unlikely to damage the device, with implications for understanding spin-mechanical effects.

Contribution

It demonstrates the mechanical stress caused by spin transfer in nanopillars and quantifies its magnitude, linking spin dynamics to mechanical effects.

Findings

Stress depends on frequency and device geometry.

Stress magnitude is about 1 MPa at GHz frequencies.

Spin transfer-induced stress is much less than internal film stress.

Abstract

We report a mechanical effect in spin-valve nanopillars due to spin transfer. A polarized current carrying electron spins transfers torque to local magnetization and leads to a magnetic switching of free layer. Like classical Einstein-de Haas effect, the conservation of angular momentum needs the free layer to offset the change of angular momentum and then a mechanical rotation occurs. The free layer is not free standing, so the mechanical angular momentum will be revealed as stress and strain. We study the effect of a spin induced stress in a nanopillar device with in-plane magnetization. Our calculations show that the tress in as device is dependent on frequency and the ratio of length/thickness and about 1 MPa at GHz. It is concluded that the stress owing to spin transfer is much less than the internal stress of film and does not introduce damage to the device.