Possible experimental realization of a basic Z2 topological semimetal in GaGeTe

Erik Haubold,Bernd Büchner,Anna Isaeva,Yevhen Kushnirenko,Alexander Fedorov,Evgueni V Chulkov,Viola Duppel,Igor P Rusinov,Setti Thirupathaiah,Daniel Friedrich,Florian Pielnhofer,Emile Rienks,Richard Weihrich,Arno Pfitzner,Timur Kim,Alexander Zeugner,Tatiana V Menshchikova,Sergey Borisenko

doi:10.1063/1.5124563

Abstract

We report experimental and theoretical evidence that GaGeTe is a basic Z2 topological semimetal with three types of charge carriers: bulk-originated electrons and holes as well as surface state electrons. This electronic situation is qualitatively similar to the classic 3D topological insulator Bi2Se3, but important differences account for an unprecedented transport scenario in GaGeTe. High-resolution angle-resolved photoemission spectroscopy combined with advanced band structure calculations show a small indirect energy gap caused by a peculiar band inversion at the T-point of the Brillouin zone in GaGeTe. An energy overlap of the valence and conduction bands brings both electron and holelike carriers to the Fermi level, while the momentum gap between the corresponding dispersions remains finite. We argue that peculiarities of the electronic spectrum of GaGeTe have a fundamental importance for the physics of topological matter and may boost the material’s application potential.

Highlights

We put forward GaGeTe as the first example of such conceptually different electronic situation, which we call a basic Z2 topological semimetal
This electronic situation is qualitatively similar to the classic 3D topological insulator Bi2Se3, but important differences account for an unprecedented transport scenario in GaGeTe
High-resolution angle-resolved photoemission spectroscopy combined with advanced band structure calculations show a small indirect energy gap caused by a peculiar band inversion at the T-point of the Brillouin zone in GaGeTe

Summary

Introduction

We put forward GaGeTe as the first example of such conceptually different electronic situation, which we call a basic Z2 topological semimetal. We report experimental and theoretical evidence that GaGeTe is a basic Z2 topological semimetal with three types of charge carriers: bulkoriginated electrons and holes as well as surface state electrons.

Results

Conclusion