%0 Journal Article
%K nickel
%K nickel alloys
%K Magnetic (CE)
%K Martensitic phase transitions
%A P Pörsch
%A M Kallmayer
%A T Eichhorn
%A G Jakob
%A H.J Elmers
%A C.A Jenkins
%A C Felser
%A Ramamoorthy Ramesh
%A M Huth
%B Applied Physics Letters
%D 2008
%G eng
%R 10.1063/1.2957647
%T Suppression of martensitic phase transition at the Ni2 MnGa film surface
%V 93
%X 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.