Reorientation of Spin Density Waves in Cr(001) Films induced by Fe(001) Cap Layers

TL;DR

This study investigates how ultrathin Fe cap layers influence the orientation of spin density waves in Cr(001) films, revealing a thickness-dependent reorientation transition driven by interface frustration effects.

Contribution

It demonstrates a novel reorientation transition of SDWs in Cr films induced by Fe cap layers, highlighting the role of interface steps and film thickness.

Findings

SDW wave vector aligns along one {100} direction depending on film thickness

Reorientation transition occurs at specific Cr thicknesses

Interface steps cause frustration effects leading to SDW reorientation

Abstract

Proximity effects of 20 \AA thin Fe layers on the spin density waves (SDWs) in epitaxial Cr(001) films are revealed by neutron scattering. Unlike in bulk Cr we observe a SDW with its wave vector Q pointing along only one {100} direction which depends dramatically on the film thickness t_{Cr}. For t_{Cr} < 250 \AA the SDW propagates out-of-plane with the spins in the film plane. For t_{Cr} > 1000 \AA the SDW propagates in the film plane with the spins out-of-plane perpendicular to the in-plane Fe moments. This reorientation transition is explained by frustration effects in the antiferromagnetic interaction between Fe and Cr across the Fe/Cr interface due to steps at the interface.