Critical Behavior and Magnetocaloric Effect in Co₂CrAl Heusler Alloy

Abstract

The analysis of structural, electrical transport, critical magnetic behavior, and magnetocaloric properties of Co2CrAl Heusler alloys has been conducted here. Co2CrAl full Heusler alloy has been prepared by the conventional arc melting method in Ar atmosphere and post‐annealing in a vacuum‐sealed quartz tube. X‐ray diffraction (XRD) pattern reveals the crystallization of the alloy to the Fm3¯m space group with L21 crystal symmetry. The correspondence between the magnetic and electrical transport properties of the Co2CrAl alloy has been observed. This alloy exhibits paramagnetic to ferromagnetic transition (Curie temperature) just above room temperature at around 340 K. Metallic to semiconducting transition occurs near the magnetic Curie temperature. Critical magnetic behavior has been analyzed by employing the Arrott plot, Kouvel–Fisher methods, and critical isotherm analysis. These conclude that the exchange interaction in Co2CrAl alloy follows between mean‐field theory having spin–spin long‐range interaction and the 3D Heisenberg model. The magnetocaloric effect has been explored from the isothermal magnetization data by employing Maxwell's equations. The highest magnetic entropy change is found to be ≈0.99 J (kg K)−1 for a magnetic field change of 30 kOe. A large working temperature window of 57 K is the advantage of the present alloy.

Variation of Electrical Resistivity During Magnetic Field-Induced Martensitic Transformation in Vanadium added NiMnSnB alloys

“…According to Mooij's rule, the resistivity should decrease with increasing temperature when the resistivity of the alloy exceeds 150μΩcm, regardless of the scattering mechanism of the charge carriers. The resistivity of Heusler alloys is can suitable to this rule, while it can be similar to metallic behavior, depending on the composition of the alloy [13][14][15][16]. The resistivity vs temperature curves of Ni49-xVxMn37Sn12B2 (x = 0, 1, 2, and 3) alloys are given in Figure 3.…”