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

作者：Liang Tian; Kushwaha Satya; Kim Jinwoong; Gibson Quinn; Lin Jingjing; Kioussis Nicholas; Cava Robert J; Ong N Phuan^*

来源：Science Advances, 2017, 3(5): e1602510.

DOI：10.1126/sciadv.1602510

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

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.

• 出版日期2017-5