Absence of magnetic-proximity effect at the interface of Bi$_2$Se$_3$ and (Bi,Sb)$_2$Te$_3$ with EuS

TL;DR

This study used XMCD to investigate magnetic proximity effects at the interface of topological insulators and EuS, finding no significant induced magnetism or enhancement of Eu magnetic moments.

Contribution

The paper provides the first element-specific XMCD analysis showing the absence of magnetic proximity effects at TI/EuS interfaces.

Findings

No significant induced magnetism in TIs

No enhancement of Eu magnetic moments

Magnetic moments below detection limit of 10^{-3} μ_B/atom

Abstract

We performed x-ray magnetic circular dichroism (XMCD) measurements on heterostructures comprising topological insulators (TIs) of the (Bi,Sb)$_2$(Se,Te)$_3$ family and the magnetic insulator EuS. XMCD measurements allow us to investigate element-selective magnetic proximity effects at the very TI/EuS interface. A systematic analysis reveals that there is neither significant induced magnetism within the TI nor an enhancement of the Eu magnetic moment at such interface. The induced magnetic moments in Bi, Sb, Te, and Se sites are lower than the estimated detection limit of the XMCD measurements of $\sim\!10^{-3}$ $\mu_\mathrm{B}$/at.