Austenitic Anisotropy Constants

Ni2MnGa Austenitic Anisotropy Constants

The austenitic phase of Ni2MnGa has a cubic Heusler structure. Cubic magnetocrystalline anisotropy constants K1 and K2 were determined for a range of temperatures from room temperature down to the transformation temperature. The constants were calculated from a series of M-H curves performed on a circular disk specimen with <110> normal. M-H curves were recorded using a custom cooling enclosure designed for use with the vibrating sample magnetometer (VSM) at the Institute for Rock Magnetism.

The VSM and a schematic of the cooling device are shown on the right.

The results of the M-H curves show that Ni2MnGa has <100> easy axes in the austenitic phase, with a relatively weak room temperature constant of K1 = 2.7 x 104 ergs/cc. The graph on the left shows the M-H curves for <100>, <110>, and <111> directions performed at -9°C just prior to the martensitic transformation. The graph on the right shows the calculated K1 value as a function of temperature. A schematic of the M-H curve disk specimen is shown below this graph.


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