Arxiv Selection Nov 2019

Nov 1-Nov 7 Zehan Li, Nov 8- Nov 14 Jiansong Pan, Nov 15- Nov 21 Ahmet Keles, Nov 22 - Nov 28 Haiping Hu

arXiv:1910.14606 (cross-list from cond-mat.mes-hall) [pdf, other]

Non-Hermitian topological phase transitions for quantum spin Hall insulators

Junpeng Hou, Ya-Jie Wu, Chuanwei Zhang

Comments: 10 pages, 9 figures

Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Gases (cond-mat.quant-gas); Optics (physics.optics)

The interplay between non-Hermiticity and topology opens an exciting avenue for engineering novel topological matter with unprecedented properties. While previous studies have mainly focused on one-dimensional systems or Chern insulators, here we investigate topological phase transitions to/from quantum spin Hall (QSH) insulators driven by non-Hermiticity. We show that a trivial to QSH insulator phase transition can be induced by solely varying non-Hermitian terms, and there exists exceptional edge arcs in QSH phases. We establish two topological invariants for characterizing the non-Hermitian phase transitions: i) with time-reversal symmetry, the biorthogonal Z2 invariant based on non-Hermitian Wilson loops, and ii) without time-reversal symmetry, a biorthogonal spin Chern number through biorthogonal decompositions of the Bloch bundle of the occupied bands. These topological invariants can be applied to a wide class of non-Hermitian topological phases beyond Chern classes, and provides a powerful tool for exploring novel non-Hermitian topological matter and their device applications.