DFT studies on electronic, magnetic and thermoelectric properties of half Heusler alloys XCaB (X = Li, Na, K and Rb)

Abstract

In this work, the results of first principles calculations of structural, electronics, magnetic and thermoelectric properties of half Heusler alloys XCaB (X = Li, Na, K and Rb) are presented. The pseudopotential method as implemented in the Quantum Espresso package has been used with the exchange correlation functional of Perdew, Burke and Ernzerhof (PBE). The total energy calculations show that the proposed alloys are in stable ferromagnetic phase and the calculated equilibrium lattice constant are in good agreement with the earlier reported results. All the alloys show strong spin polarisation of energy states near the Fermi level confirming ferromagnetic nature and also semiconducting for majority spin channel and metallic for down spin channel exhibiting half metallic property. The calculated magnetic moment of all the alloys XCaB (X = Li, Na, K and Rb) is around 2.00 µB mainly arises from the np electrons of B atom with partial involvement of nd electrons of Ca atom. The thermoelectric properties of the materials are calculated using the BoltzTrap code. The calculated transport properties like electrical conductivity, thermal conductivity and power factor increases with temperature which is a perfect fit for thermoelectric applications. The half metallic gap, strong spin polarization and high figure of merit (ZT) values shows that these studied materials can be used for both spintronics and thermoelectric device applications.