Investigation of structural, electronic and magnetic properties of 1:1:1:1 stoichiometric quaternary Heusler alloys YCoCrZ (Z=Si, Ge, Ga, Al): An ab-initio study

摘要

Full potential linearized augmented plane wave method (FPLAPW) has been employed to probe the structural, electronic and magnetic properties of equiatomic yttrium based quaternary Heusler alloys YCoCrZ (Z=Si, Ge, Ga, Al). These calculations have been carried out via ab -initio simulations based on density functional theory (DFT) approach coded by Wien2K. The generalized gradient approximation of Perdew-Burke-Ernzerhof 96 scheme is engaged for calculations in all alloys under investigation. Equilibrium lattice constants are studied by structural optimization performed by computing total energies versus volumes. Structural optimization demonstrates that Y(3/4,3/4,3/4)Co(0,0,0)Cr(1/2,1/2,1/2)Z(1/4,1/ 4,1/4) (Type-1) configuration is the most stable one. The calculated electronic and magnetic properties based on type-1, indicate that YCoCrZ alloys are half-metallic ferromagnetic. The calculation of spin polarization is also made and further their total magnetic moments follow the Slater Pauling rule of M_(tot) =N_(VE)-18 conceding the integer value i.e. 4.00 μ_B and 3.00 μ_B for YCoCrSi, Ge and YCoCrGa, Al respectively. The results of density of states (DOS) revealed that yttrium based quaternary Heusler alloys exhibit excellent band gaps i.e. 0.70,0.65,0.46 and 0.35 eV for YCoCrSi, Ge, Ga and Al respectively. The formation of band gaps owing to hybridization effect is also described. The half-metallic gaps of these compounds comprising the order YCoCrGa ＞ YCoCrSi ＞ YCoCrAl ＞ YCoCrGe by size, is also manipulated. The incredible spin gapless semiconductor (SGS) type character of YCoCrGa and YCoCrAl having bantam DOS in spin up version is also discoursed. The optimised results of these compounds signpost that these are suitable candidates for spintronics applications.