Landau level spectroscopy of PbSnSe topological crystalline insulator

TL;DR

This study uses infrared magneto-spectroscopy to analyze Landau levels in PbSnSe topological crystalline insulators, revealing a relativistic-like behavior of bulk electrons without clear signs of surface states.

Contribution

It provides a detailed Landau level spectroscopy analysis of PbSnSe, modeling bulk electronic states with a relativistic Hamiltonian including quadratic terms, and discusses the absence of expected surface states.

Findings

Bulk electrons behave like massive Dirac particles.

No clear evidence of massless surface states detected.

Band inversion effects are modeled with quadratic Hamiltonian terms.

Abstract

We report on an infrared magneto-spectroscopy study of Pb$_{1-x}$Sn$_x$Se, a topological crystalline insulator. We have examined a set of samples, all in the inverted regime of electronic bands, with the tin composition varying from $x=0.2$ to $0.33$. Our analysis shows that the observed response, composed of a series of interband inter-Landau level excitations, can be interpreted and modelled using the relativistic-like Hamiltonian for three-dimensional massive Dirac electrons, expanded to include diagonal quadratic terms that impose band inversion. In our data, we have not found any clear signature of massless electron states that are present on the surface of Pb$_{1-x}$Sn$_x$Se crystals in the inverted regime. Reasons for this unexpected result are discussed.