Critical behaviour and magnetocaloric properties of hexagonal MnCo0.7Fe0.3Ge

Abstract

The structural and magnetic properties of MnCo0.7Fe0.3Ge are investigated using x-ray diffraction and magnetization measurements. The alloy crystallizes in Ni2In-type hexagonal structure with P63/mmc space group and exhibits ferromagnetic ordering at 245 K with a saturation magnetization of about 2.73 μB/f.u. The critical exponents (β = 0.42 ± 0.02, γ = 1.42 ± 0.07, δ = 4.38 ± 0.32) and the critical temperature (TC ∼ 243 K) obtained through Modified Arrott’s plot (MAP) and Kouvel-Fisher (KF) methods are found to be self-consistent. A maximum magnetic entropy change of about ΔSmag = −4.93 J.kg−1.K−1 is noticed under the influence of 90 kOe. The critical exponents which are obtained through magnetocaloric method are in good agreement with those obtained through MAP and KF methods. The exponents indicate 3D-Heisenberg universality class with short range magnetic interaction, as inferred from the exchange interactions J(r) ∼ r−5.04.