Revealing the spin and symmetry properties of the buried Co2MnSi/MgO interface by low energy spin-resolved photoemission

TL;DR

This paper introduces a new low-energy spin-resolved photoemission technique to non-destructively analyze the spin and symmetry properties of buried magnetic interfaces, demonstrated on Co2MnSi/MgO, revealing key electronic structure details relevant for spintronics.

Contribution

The study presents a novel method for probing buried interfaces' spin and symmetry properties, enabling non-destructive analysis of magnetic tunnel junction components.

Findings

Surface state with Δ1 symmetry and minority spin is quenched at the interface.

Interface electronic structure resembles bulk Co2MnSi band structure.

Thermally-induced minority channel contribution reflects majority channel asymmetry.

Abstract

We present a novel approach to study the spin and symmetry electronic properties of buried interfaces using low-energy spin-resolved photoemission spectroscopy. We show that this method is sensitive to interfaces buried below more than 20ML (~4nm) MgO, providing a powerful tool for the non-destructive characterization of spintronics interfaces. As a demonstration, we apply this technique to characterize the Co2MnSi/MgO interface, a fundamental building block of state-of-the-art magnetic tunnel junctions based on Heusler compounds. We find that a surface state with {\Delta}1 symmetry and minority spin character dominating the electronic structure of the bare Co2MnSi(100) surface is quenched at the Co2MnSi(100)/MgO interface. As a result, the interface spin-dependent electronic structure resembles the theoretically expected Co2MnSi bulk band structure, with majority spin electronic states of both {\Delta}1 and {\Delta}5 symmetry. Furthermore we find an additional thermally-induced contribution in the minority channel, mirroring the {\Delta}1/{\Delta}5 asymmetry of the majority channel.