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Structural, magnetic and phase transformation properties of Fe-Pd thin films processed and characterized in situ with micro-hotplates
|Sven Hamann 1,2, Hayo Brunken 1,2, Michael Ehmann 1, Sigurd Thienhaus 1,2, Alan Savan 1, Alfred Ludwig 1,2|
1. center of advanced european studies and research (caesar), Ludwig-Erhard-Allee 2, Bonn 53175, Germany
Fe-Pd thin films were fabricated by sequential sputtering of elemental and alloy targets on micro-hotplate (MHP) arrays, in order to investigate their properties as ferromagnetic shape memory alloys (FSMA). The advantages of Fe-Pd-based FSMA in comparison to Ni-Mn-Ga are a higher Curie temperature, saturation magnetization, transformation temperature as well as potentially higher magnetocrystalline anisotropy. The micro-hotplates – microstructured Si3N4 and SiO2 membranes with Pt heaters and measurement electrodes – were used as material processing and characterization platforms: Films on such MHPs can be heated and cooled with rates up to several 1000K/s which enables rapid and precise annealing and quenching of metastable phases. Furthermore, during the heat treatment, the resistance of the thin film on the MHPs can be monitored, so that phase transformations can be identified in situ. The films were characterized by energy disperse x-ray spectroscopy, x-ray diffraction, resistance versus temperature measurements and temperature dependent vibrating sample magnetometry measurements. First results of MHP-processed Fe-Pd thin films show a reversible phase transformation with low hysteresis in a composition range from Fe70Pd30 to Fe72Pd28 in a temperature interval from 50°C to 90°C.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium E, by Sven Hamann
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 21:22 Revised: 2009-06-07 00:44