Bulk Signatures of Pressure-Induced Band Inversion and Topological Phase   Transitions in Pb$_{1-x}$Sn$_x$Se
  The characteristics of topological insulators are manifested in both their surface and bulk properties, but the latter remain to be explored. Here we report bulk signatures of pressure-induced band inversion and topological phase transitions in Pb$_{1-x}$Sn$_x$Se ($x=$0.00, 0.15, and 0.23). The results of infrared measurements as a function of pressure indicate the closing and the reopening of the band gap as well as a maximum in the free carrier spectral weight. The enhanced density of states near the band gap in the topological phase give rise to a steep interband absorption edge. The change of density of states also yields a maximum in the pressure dependence of the Fermi level. Thus our conclusive results provide a consistent picture of pressure-induced topological phase transitions and highlight the bulk origin of the novel properties in topological insulators. 
Xiaoxiang Xi, Xu-Gang He, Fen Guan, Zhenxian Liu, R. D. Zhong, J. A.   Schneeloch, T. S. Liu, G. D. Gu, D. Xu, Z. Chen, X. G...
cond-mat.mtrl-sci