Regular Article

First principles study on the structural, electronic, magnetic and thermoelectric properties of CoX′NbGa (X′ = Cr, Mn, Fe) quaternary Heusler alloys^★

Department of Theoretical Physics, University of Madras, Guindy Campus, Chennai 600025, India

^a e-mail: ritajohn.r@gmail.com

Received: 12 November 2018
Received in final form: 8 March 2019
Published online: 15 April 2019

Abstract

In this report, the structural, electronic, magnetic and thermoelectric properties of CoX′NbGa (X′ = Cr, Mn, Fe) quaternary Heusler alloys are investigated using the full potential linearized augmented plane wave method in combination with the semi-classical Boltzmann transport theory. The exchange and correlation effects are treated using generalized gradient approximation and modified Becke-Johnson scheme. Our results reveal that CoCrNbGa and CoFeNbGa are half-metallic ferrimagnets satisfying the well-known Slater Pauling rule M_t = Z_t − 24 from the analysis of electronic and magnetic properties. The half-metallic behaviour of CoCrNbGa and CoFeNbGa are robust against hydrostatic strain for a considerably wide range of lattice constants which makes them potential candidates for spintronic applications. CoMnNbGa is a non-magnetic 24 valence electron semiconductor and has better thermoelectric performance than CoCrNbGa and CoFeNbGa.