The thermal expansion coefficient and volume magnetostriction of Heusler Ni 2MnGa alloys

Abstract

In this work the thermal expansion coefficient of Ni 2MnGa alloy was experimentally determined. It was shown that the thermal expansion coefficient has a peak at the point of magnetic phase transition. The value of thermal expansion coefficient jump at Curie point is Δ κ=1.8×10 −5 K −1. From the phenomenological Ginzburg–Landau theory of a magnetic second-order phase transition the expression for a jump of thermal expansion coefficient in Curie point was obtained. From the comparison of experimental and theoretical jumps of thermal expansion the value of volume magnetostriction for Ni 2MnGa alloy was determined: B 1≈20×10 9 erg/cm 3.