Magneto-Caloric effect and Multiple magnetic phases in Al doped Ni2MnSn0.75Al0.25 Heusler Alloys

Abstract

Among Heusler compounds,Ni based alloys have been extensively investigated because they exhibit desirable properties such as high Curie temperatures, which are advantageous for advanced magnetic and spintronic devices.The effect of Al substitution on the magnetic ground state of Ni2MnSn was investigated using the Ni2MnSn0.75Al0.25 Heusler alloy.Temperature-dependent magnetisation measurements identify a second-order paramagnetic to ferromagnetic transition at TC is 734K,followed by a first-order martensitic transformation near 263K,demonstrating strong magnetostructural coupling.Curie Weiss analysis yields a positive Weiss temperature theta CW is 746.4K and an effective magnetic moment of 6.82muB,confirming the predominance of ferromagnetic exchange interactions. The bifurcation between the ZFC and FCW magnetization curves,together with non saturating hysteretic M vs H loops, indicates the coexistence of competing ferromagnetic and antiferromagnetic interactions.Further magnetic investigations establish the formation of an interacting reentrant cluster glass state accompanied by an exchange-bias effect.The observed magnetic behavior is attributed to the modification of Mn Mn exchange interactions induced by Al substitution and the associated atomic disorder,resulting in a complex magnetic ground state.