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Properties of martensitic Ni-Mn-Ga thin films deposited on Mo foils
|Concepcio Seguí 3, Volodymyr A. Chernenko 4, Manfred Kohl 1, Makoto Ohtsuka 2, J Pons 3, Eduard Cesari 3
1. Forschungszentrum Karlsruhe, IMT, Postfach 3640, Karlsruhe 76021, Germany
Recently the Ni-Mn-Ga ferromagnetic martensites with unique magnetomechanical properties are subject of intense development in polycrystalline thin film form, because they can be used as innovative component materials in nanosystems. Understanding of the fundamental relationship between their size, shape, structure and material properties and function is a crucial point to be clarified. This paper deals with the investigation of the structural (X-rays and electron diffraction), elastic (dynamical mechanical analysis, DMA), magnetic (SQUID) and magnetomechanical (beam bending tests) characteristics exhibited by submicron Ni-Mn-Ga thin films deposited and annealed on Mo foils of 5 and 10 micron thickness. Film series with two different compositions and thickness 0.1; 0.4 and 1 micron were prepared by r.f. magnetron sputtering. The crystal structure of martensitic phase in each film series is 10M or 14M, respectively. The magnetic characteristics are the typical for bulk Ni-Mn-Ga alloys. The temperature dependences of DMA signal performed in tensile mode have shown that composites of Ni-Mn-Ga thin film/Mo foil exhibit a hysteretic martensitic transformation accompanied by well pronounced step-like anomalies. The low-frequency elastic modulus is larger in austenite state than in martensitic one. Magnetoelastic measurements revealed a magnetic field-induced bending of bimetallic-type specimens with the estimated value of magnetostrain in Ni-Mn-Ga layer to be about 0.1 %.
Presentation: poster at E-MRS Fall Meeting 2005, Symposium C, by Concepcio Seguí
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-30 09:58 Revised: 2009-06-07 00:44