Effect of atomic disorder on magnetization and half-metallic character of Cr2CoGa alloy

• Low magnetic moment of 0.26μB/f.u. is reported for for Cr2CoGa alloy.
• Amount of Cr(B)–Ga disorder in Cr2CoGa is determined by XRD analysis.
• Cr(B)–Ga and Cr(B)–Co disorders result in non-zero moment of the alloy.

Crystallographic, magnetic and transport properties of bulk Cr2CoGa alloy are reported in this work. The alloy exhibits inverse Heusler (or XA) structure. Analysis of XRD pattern reveals the presence of 10% Cr(B)–Ga disorder in the alloy. Lattice constant of the alloy was found to be 5.80 Å. The alloy exhibits ferrimagnetic behavior with Curie temperature (TC) of 320 K as obtained from the thermo-magnetic measurement and temperature dependent inverse susceptibility for the alloy. The saturation magnetization Ms for the alloy was found to be 0.26 μB/f.u. at 25 K against the value of 0 μB/f.u. predicted by Slater-Pauling rule. This deviation is attributed to the presence of Cr(B)–Ga disorder along with a small amount of Cr(B)–Co disorder in the alloy. The temperature dependent resistivity data shows a T2 dependency in low temperature region predicting that the charge carriers are not completely spin polarized at Fermi level due to the presence of sub-lattice disorder. Linear variation of resistivity above 100 K indicates the main contribution is from scattering of electrons by phonons. The effective anisotropy of the alloy was low (1.2×104 Jm−3 at 25 K) mainly due to its low Ms.