Reversible magnetocaloric effect and critical exponent analysis in Mn-Fe-Ni-Sn Heusler alloys

We report the magnetic and magnetocaloric properties of Mn48-xFexNi41Sn11 (x = 8.5, 10.5) Heusler alloys. The temperature dependent magnetization curve (M vs T curve) reveals that these alloys show only second order ferromagnetic (FM) to paramagnetic (PM) transition at their Curie temperature (TC) and no structural transformation is observed. A large value of saturation magnetization (MS) ∼ 72.76 Am2/kg is observed at 80 K for x = 8.5 alloy as the alloy becomes purely austenite for this composition. A reversible magnetic entropy change of 1.02 JKg−1K−1 with moderate refrigerant capacity (RC) ∼ 40.2 J/kg are obtained near room temperature (∼305 K) for x = 8.5, across its TC due to a field change of 14 kOe only. The critical exponents are calculated for both the samples and found to exhibit long range ferromagnetic ordering in their austenite phase.