Electronic structure of SrSn2As2 near the topological critical point

L.-Y Rong,X.-Z Zhang,H.-M Weng,Z.-L Li,J.-Z Ma,R.-Z Tai,Y.-B Huang,B.-B Fu,S.-M Nie,L.-Y Kong,T Qian,H Ding,Z.-P Lin

doi:10.1038/s41598-017-05386-x

Abstract

Topological materials with exotic quantum properties are promising candidates for quantum spin electronics. Different classes of topological materials, including Weyl semimetal, topological superconductor, topological insulator and Axion insulator, etc., can be connected to each other via quantum phase transition. For example, it is believed that a trivial band insulator can be twisted into topological phase by increasing spin-orbital coupling or changing the parameters of crystal lattice. With the results of LDA calculation and measurement by angle-resolved photoemission spectroscopy (ARPES), we demonstrate in this work that the electronic structure of SrSn2As2 single crystal has the texture of band inversion near the critical point. The results indicate the possibility of realizing topological quantum phase transition in SrSn2As2 single crystal and obtaining different exotic quantum states.

Highlights

Topological materials attract much attention because of their exotic characters including non-trivial Dirac surface state, magnetic monopole Fermi arc and so on[1,2,3,4,5,6,7]
When we redo the calculation with the modified Becke-Johnson exchange potential[33], the topological state is different as shown in Fig. 1(c), we get a trivial insulator with no band inversion, which means that this crystal can theoretically be tuned from a strong topological insulator into a trivial insulator
We identify three Γ-centered bands crossing EF, the inner one marked as α is an electron band, the outer ones marked as β and γ are hole-like bands. α and β band contribute to two small Fermi surface pockets around Brillouin Zone (BZ) center marked as α BFS and β BFS in Fig. 2(a) while γ forms the big flower like Fermi surface marked as γ SFS

Summary

Introduction

Topological materials attract much attention because of their exotic characters including non-trivial Dirac surface state, magnetic monopole Fermi arc and so on[1,2,3,4,5,6,7] This field has enjoyed rapid development in recent years thanks to the well agreement and effective mutual promotion between experimental observation and theoretical calculation. Among the families of topological materials, topological insulator is a novel state of matter It has an energy gap in the bulk like ordinary insulators but gapless Dirac fermionic states on the boundaries. At this critical point the system turns into the well-known Dirac semimetal. Our study shows that the single crystal SrSn2As2 is probably a new topological insulator near the topological critical point

Methods

Results

Conclusion