Pressure induced semimetallic B2 phase of alkaline earth tellurides

Abstract

Abstract We report pressure induced structural, topological quantum phase transitions and Fermi surface topology in MTe (M = Ca, Sr, Ba) compounds under high pressure using first principles calculations based on density functional theory. MTe compounds undergo a first order structural phase transition from NaCl-type (B1) to CsCl-type (B2) phase at 24.2, 14.7, 4.9 GPa respectively and are consistent with the experimental observations. Electronic structure of MTe compounds were calculated using new parameterization of Tran Blaha-modified Becke Johnson (TB-mBJ) potential and the obtained band gaps are improved over LDA/GGA functionals. The three compounds under investigation are indirect band gap semiconductors at ambient conditions. Under high pressure, B2 phase of (Ca/Sr)Te and BaTe are found to be node-line and Dirac semimetals, respectively without inclusion of spin-orbit coupling.