Predicting ferromagnetism and thermoelectric characteristics in bulk spinels ZnCr2X4 (X = S, Se) using density functional theory

Abstract

To have control over the properties of electronic devices with the help of the spin of electrons is considered an amalgamation field of innovative technology. The thermoelectric and ferro-magnetic characteristics of bulk ZnCr2X4 (X = S, Se) spinels have been investigated by the BoltzTraP and WIEN2k codes. The optimization of the fully relaxed structures has been performed by PBE generalized gradient approximation (GGA) for the exposure of ground state parameters and our calculated results of lattice constant represent a reasonable agreement with experimental values. The comparative analysis of the energies that emerged fromnonmagnetic and ferromagnetic states using PBE-GGA shows that the state is the ferromagnetic. The modified Becke-Johnson local density approximation (mBJLDA) has been brought into use for the computation of the density of states (DOS) and precise band structures (BS), which authenticates the ferromagnetic semiconducting behavior. Further, the calculation of exchange splitting energies, John-Teller energy, and crystal field energy explored the origin of ferromagnetism. The strong hybridization resulting in decomposition in Cr, the magnetic moment and creates the magnetic moments at the nonmagnetic sites. Consequently, the thermoelectric characteristichas been explored by the BoltzTraP code that reveals that the increasing temperature increases the power factor, the thermal conductivity, and the electrical conductivity whereas the Seebeck coefficient reduces with it. However, the compounds in our study prove to be suitable for being used in thermoelectric devices for alternative energy resources.