Magnetic dichroism in angular-resolved hard X-ray photoelectron spectroscopy from buried layers

TL;DR

This study demonstrates the use of hard X-ray photoelectron spectroscopy with circular polarization to detect magnetic dichroism in buried magnetic layers, revealing magnetic properties and moments in complex multilayer structures.

Contribution

It introduces a method to measure magnetic dichroism in buried layers using high-energy HAXPES with circularly polarized light, enabling investigation of magnetic properties beneath surfaces.

Findings

Magnetic dichroism observed in Co and Fe 2p states of buried layers.

Localization of magnetic moments at Fe sites in Heusler compounds.

Detection of magnetic properties in multilayer structures with buried layers.

Abstract

This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard X-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co$_2$FeAl layer buried beneath the IrMn layer. A pronounced magnetic dichroism is found in the Co and Fe $2p$ states of both materials. The localization of the magnetic moments at the Fe site conditioning the peculiar characteristics of the Co$_2$FeAl Heusler compound, predicted to be a half-metallic ferromagnet, is revealed from the magnetic dichroism detected in the Fe $2p$ states.