Suppression of martensitic phase transition at the Ni2 MnGa film surface

Journal Article

Pörsch, P., M. Kallmayer, T. Eichhorn, G. Jakob, H.J. Elmers, C.A. Jenkins, C. Felser, Ramamoorthy Ramesh, M. Huth

10.1063/1.2957647

We investigated magnetic and structural properties at the surface of epitaxial Ni2 MnGa (110) Heusler films using x-ray absorption spectroscopy and x-ray magnetic circular dichroism both in transmission and total electron yield mode. The magnetic shape memory films were prepared by dc sputtering from a stoichiometric target onto sapphire substrates at an optimized substrate temperature of 773 K. X-ray diffraction confirms a (110) oriented growth on Al2 O3 (11 2- 0) and an austenite to martensite transition at 270-280 K. At the surface the martensitic phase transition and the magnetization are strongly suppressed. The deviation in the surface properties is caused by a Mn deficiency near the surface. © 2008 American Institute of Physics.

Applied Physics Letters

93

2008

00036951

Ramesh Lab