Search results for "Shape-memory alloy"
showing 4 items of 24 documents
Strain-Controlled Giant Magnetoresistance in Spin Valves Grown on Shape Memory Alloys
2019
We report a strain-mediated giant magnetoresistance (GMR) in spin valves (SPVs) grown on shape memory alloys (SMAs). The SPVs with a stacking structure of Al2O3/Co90Fe10/Cu/Co90Fe10/IrMn/Pt were de...
Full Tunability of Strain along the fcc-bcc Bain Path in Epitaxial Films and Consequences for Magnetic Properties
2009
Strained coherent film growth is commonly either limited to ultrathin films or low strains. Here, we present an approach to achieve high strains in thicker films, by using materials with inherent structural instabilities. As an example, 50 nm thick epitaxial films of the ${\mathrm{Fe}}_{70}{\mathrm{Pd}}_{30}$ magnetic shape memory alloy are examined. Strained coherent growth on various substrates allows us to adjust the tetragonal distortion from $c/{a}_{\mathrm{bct}}=1.09$ to 1.39, covering most of the Bain transformation path from fcc to bcc crystal structure. Magnetometry and x-ray circular dichroism measurements show that the Curie temperature, orbital magnetic moment, and magnetocrysta…
Magnetic and Electronic Properties of Heusler Alloy Films Investigated by X-Ray Magnetic Circular Dichroism
2008
We have investigated the magnetic properties of epitaxial Heusler alloy films using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism∈dex{x-ray!magnetic circular dichroism} (XMCD) in the transmission (TM) and in the surface sensitive total electron yield (TEY) mode. We have investigated Ni_2MnGa based shape memory alloys and half-metallic Co2Cro.6Feo.4 films. Single crystalline Ni2MnGa(110)/Al2O3(1120) and Ni2MnGa(100)/MgO(100) films show a martensitic transition from a cubic high temperature phase to a martensitic low-temperature phase at 250–275 K as concluded from magnetometry and x-ray diffraction. The martensitic transition of this Heusler compound is shifted in…
Collective Modes and Structural Modulation in Ni-Mn-Ga(Co) Martensite Thin Films Probed by Femtosecond Spectroscopy and Scanning Tunneling Microscopy.
2015
International audience; The origin of the martensitic transition in the magnetic shape memory alloy Ni-Mn-Ga has been widely discussed. While several studies suggest it is electronically driven, the adaptive martensite model reproduced the peculiar nonharmonic lattice modulation. We used femtosecond spectroscopy to probe the temperature and doping dependence of collective modes, and scanning tunneling microscopy revealed the corresponding static modulations. We show that the martensitic phase can be described by a complex charge-density wave tuned by magnetic ordering and strong electron-lattice coupling.