First-Principles Investigation of Zr-Based Equiatomic Quaternary Heusler Compounds Under Hydrostatic Pressure for Spintronics Applications

The first-principles method using density functional theory (DFT) reveals the mechanics, electronic structure, and magnetic properties of six Zr-based equiatomic quaternary Heusler compounds and their transformation under hydrostatic pressure. The results show that these compounds maintain mechanical stability under hydrostatic pressures of 0-100 GPa, and the ductility of all the alloys is improved except ZrCrFeGe. In the ground state structure, ZrVFeAl and ZrCrFeGe are half metals, ZrVCoAl and ZrCrFeAl are spin gapless semiconductors, while ZrCrMnAl and ZrMnFeAl are regarded as nearly half metals. ZrVFeAl, ZrVCoAl, ZrCrFeAl, and ZrCrFeGe have high spin polarization and satisfy the Slater-Pauling rule, and their spin-flip band gaps are 0.43 eV, 0.35 eV, 0.14 eV, and 0.11 eV, respectively. These half-metallic compounds maintain half-metallicity within a certain pressure range, while spin gapless semiconductors (SGS) complete the SGS~half-metal~near-half-metal transition under hydrostatic pressure. These half-metallic compounds and spin gapless semiconductors are ideal candidates for spintronic applications.