Unusual surface states associated with the PT-symmetry breaking and antiferromagnetic band folding in NdSb

TL;DR

This study uses micro-focused ARPES to explore surface states in NdSb, revealing how PT-symmetry breaking and antiferromagnetic band folding influence surface electronic structures across different magnetic domains.

Contribution

It provides the first detailed observation of surface states associated with PT-symmetry breaking and antiferromagnetic band folding in NdSb, highlighting domain-dependent surface state symmetries.

Findings

Surface states show twofold symmetry in in-plane AF domains.

Surface states exhibit fourfold symmetry in out-of-plane AF domain.

PT-symmetry breaking and band folding are key to surface state formation.

Abstract

We have performed micro-focused angle-resolved photoemission spectroscopy on NdSb which exhibits the type-I antiferromagnetism below TN = 16 K. We succeeded in selectively observing the band structure for all three types of single-q antiferromagnetic (AF) domains at the surface. We found that two of the three surfaces whose AF-ordering vector lies within the surface plane commonly show twofold symmetric surface states (SSs) around the bulk-band edges, whereas the other surface with an out-of-plane AF-ordering vector displays fourfold symmetric shallow electronlike SS at the Brillouin-zone center. We suggest that these SSs commonly originate from the combination of the PT (space-inversion and time-reversal) symmetry breaking at the surface and the band folding due to the AF order. The present results pave a pathway toward understanding the relationship between the symmetry and the surface electronic states in antiferromagnets.