Enhancement in structural order and half-metallicity by V substitution for Co in Co2MnAl alloy

Abstract

In an attempt to enhance the spin polarization of Co₂MnAl Heusler alloys, a series of bulk Co_2-xMnV_xAl (for x = 0.0, 0.25, and 0.50) alloys have been prepared and studied. Structural investigations revealed a B2-type partially disordered structure in the alloys with x = 0.0 and 0.25, whereas the alloy with x = 0.50 displayed L2₁–type structure with high ordering. The saturation magnetization values of 3.91 ± 0.04, 2.45 ± 0.04, and 1.48 ± 0.03 μ_B/f.u. were observed at 10 K for the alloys with x = 0.0, 0.25, and 0.50, respectively. With progressive incorporation of V for Co, the Curie temperature decreased from 690 K to 533 K along with a decrease in effective magnetic anisotropy constant. The first-principles calculations predict a rise in spin polarization from ∼69 % for x = 0.0 to 100 % for the alloy with x = 0.50. The enhancement in spin polarization predicted in Co_1.5MnV_0.5Al alloy was experimentally validated by the appropriate Rhodes-Wohlfarth ratio evaluated for this alloy, which projects it as a promising contender for applications in spintronic devices.