Spin-polarized (001) surface states of the topological crystalline insulator Pb_{0.73}Sn_{0.27}Se

TL;DR

This paper investigates the (001) surface states of Pb_{0.73}Sn_{0.27}Se, revealing both metallic topological states with chiral spin textures and gapped trivial states, supported by theoretical predictions and experimental spectroscopy evidence.

Contribution

It provides the first combined theoretical and experimental analysis of surface states in Pb_{0.73}Sn_{0.27}Se across topological and trivial phases.

Findings

Metallic surface states with chiral spin structure in the TCI phase

Nonmetallic, gapped surface states with spin polarization in the trivial phase

Experimental confirmation of surface states and their spin textures

Abstract

We study the nature of (001) surface states in Pb_{0.73}Sn_{0.27}Se in the newly discovered topological-crystalline-insulator (TCI) phase as well as the corresponding topologically trivial state above the band-gap-inversion temperature. Our calculations predict not only metallic surface states with a nontrivial chiral spin structure for the TCI case, but also nonmetallic (gapped) surface states with nonzero spin polarization when the system is a normal insulator. For both phases, angle- and spin-resolved photoelectron spectroscopy measurements provide conclusive evidence for the formation of these (001) surface states in Pb_{0.73}Sn_{0.27}Se, as well as for their chiral spin structure.