Research ArticleMATERIALS SCIENCE

A pressure-induced topological phase with large Berry curvature in Pb1−xSnxTe

+ See all authors and affiliations

Science Advances  31 May 2017:
Vol. 3, no. 5, e1602510
DOI: 10.1126/sciadv.1602510

You are currently viewing the abstract.

View Full Text

Abstract

The picture of how a gap closes in a semiconductor has been radically transformed by topological concepts. Instead of the gap closing and immediately reopening, topological arguments predict that, in the absence of inversion symmetry, a metallic phase protected by Weyl nodes persists over a finite interval of the tuning parameter (for example, pressure P). The gap reappears when the Weyl nodes mutually annihilate. We report evidence that Pb1−xSnxTe exhibits this topological metallic phase. Using pressure to tune the gap, we have tracked the nucleation of a Fermi surface droplet that rapidly grows in volume with P. In the metallic state, we observe a large Berry curvature, which dominates the Hall effect. Moreover, a giant negative magnetoresistance is observed in the insulating side of phase boundaries, in accord with ab initio calculations. The results confirm the existence of a topological metallic phase over a finite pressure interval.

Keywords
  • Topological phases of matter
  • Berry curvature
  • anomalous Hall effect
  • PbSnTe
  • Gap tuning by pressure
  • Weyl fermions
  • giant magnetoresistance

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

View Full Text