Magnetic properties of Heusler compounds Co1+xCrAl (x = 0, 0.25, 0.5, 0.75, 1)

The compounds Co _1+x CrAl (x = 0, 0.25, 0.5, 0.75 and 1) have been successfully prepared using the arc melting technique. Room temperature XRD patterns confirm that all compounds have Heusler compounds like fcc structure. Magnetic properties of all as-cast compounds have been studied and it is observed that all compounds are ferromagnetic below their respective PM-FM transition temperature (T _c ). For half Heusler compound CoCrAl, the T _c is around 14 K but H/M as a function of temperature (T) curves at high magnetic field follows the modified Curie-Weiss law above 200 K. CoCrAl and Co _1.25CrAl compounds violate the universal nature of paramagnetism (above T _c) for low magnetic field values due to the presence of magnetic clusters within the paramagnetic matrix. For the other three compounds Co _1.5CrAl, Co _1.75CrAl and Co ₂CrAl universal nature of paramagnetism and Curie-Weiss law have been satisfied properly above T _c . Except for the full Heusler compound Co ₂CrAl, the value of T _c increases with increasing Co concentration because lattice parameter and distance between magnetic ions decrease with increasing Co concentration. The saturation magnetization (M _S) of the compounds increases with increasing Co concentration within the compounds. The saturation magnetization (M _S) does not follow the well-known Slater-Pauling rule for any compounds except for CoCrAl. M−H curves for all compounds below T _c suggest the soft magnetic nature of the compounds.