Surface Spin-valve Effect

TL;DR

This paper reports the discovery of a spin-valve effect at the atomic scale at ferromagnetic interfaces, using phonon spectroscopy to localize the effect to surface layers, revealing a new mechanism for spin switching.

Contribution

It introduces a novel surface spin-valve mechanism in ferromagnetic layers, identified through phonon spectroscopy, highlighting atomic-scale surface spin layers as key to the effect.

Findings

Spin-valve like hysteresis observed at atomic interfaces.

Phonon peaks used to localize spin switching to surface layers.

Surface spin layers can form current or field driven spin valves.

Abstract

We report an observation of spin-valve like hysteresis within a few atomic layers at a ferromagnetic interface. We use phonon spectroscopy of nanometer sized point contacts as an in-situ probe to study the mechanism of the effect. Distinct in energy phonon peaks for contacts with dissimilar nonmagnetic outer electrodes allow to localize the observed spin switching to the top or bottom interfaces for nanometer thin ferromagnetic layers. The mechanism consistent with our data is energetically distinct atomically thin surface spin layers that can form current or field driven surface spin-valves within a single ferromagnetic film.