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

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 (P-s) 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 P-s and vice versa. Although the P-s can be lowered by isoelectronic substitution, the Dirac-like electronic band dispersion around P-s is exhibited only by SrTe at 17 GPa which is almost half the P-s 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.