Tuning of Structural Transition Pressure and Electronic Properties of Alkaline Earth Chalcogenides by Isoelectronic Substitution

Abstract

CaTe exhibits Dirac-like linear dispersion in a simple cubic CsCl-type structure which is stable above pressure of 33 GPa. In the present paper, we have studied all the alkaline earth metal chalcogenides to check for the possibility of a structural transition pressure (Ps) below 33 GPa and also exhibiting Dirac-like linear dispersions as in CaTe. Our results show that a larger cation or anion increases the unit cell volume and lowers the Ps and vice versa. Although the Ps can be lowered by isoelectronic substitution, the Dirac-like electronic band dispersion around Ps is exhibited only by SrTe at 17 GPa which is almost half the Ps for CaTe. Interestingly, our study finds that in absence of spin-orbit interaction all studied alkaline chalcogenides exhibit Dirac-like dispersions at pressures ranging from 17 GPa for SrTe to 650 GPa for CaS, whereas a few retain Dirac-like dispersion even under the effect of spin-orbit interaction.