Phase transitions and the magnetocaloric effect in Mn rich Ni–Mn–Ga Heusler alloys

Abstract

In Mn rich polycrystalline Heusler alloys, Ni 50Mn 25+− x Ga 25− x , prepared by Arc melting, it is found that the structural/first-order magnetic transition temperature T m increases as the Mn content increases. The Curie temperature T c is higher than that of Ni rich alloys (Ni 50+ x Mn 25− x Ga 25 ) of the same series, and is less affected by composition x. Magnetic entropy change of |Δ S M| also increases as Mn content increases, while behaviour of the field dependence of Δ S M is similar to that of single crystal Ni 52.6Mn 23.1Ga 24.3.