Filters

2012 - 20142

More filters

20202
Reset filters

Settings

Subject: Manganese × WGL Institute: IOM ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Nanoscale mechanical surface properties of single crystalline martensitic Ni-Mn-Ga ferromagnetic shape memory alloys
    (Bristol : IOP, 2012) Jakob, A.M.; Müller, M.; Rauschenbach, B.; Mayr, S.G.
    Located beyond the resolution limit of nanoindentation, contact resonance atomic force microscopy (CR-AFM) is employed for nano-mechanical surface characterization of single crystalline 14M modulated martensitic Ni-Mn-Ga (NMG) thin films grown by magnetron sputter deposition on (001) MgO substrates. Comparing experimental indentation moduli-obtained with CR-AFM-with theoretical predictions based on density functional theory (DFT) indicates the central role of pseudo plasticity and inter-martensitic phase transitions. Spatially highly resolved mechanical imaging enables the visualization of twin boundaries and allows for the assessment of their impact on mechanical behavior at the nanoscale. The CR-AFM technique is also briefly reviewed. Its advantages and drawbacks are carefully addressed.
  • Thumbnail Image
    Item
    Electronic transitions and dielectric function tensor of a YMnO3 single crystal in the NIR-VUV spectral range
    (London [u.a.] : Royal Society of Chemistry, 2014) Schmidt-Grund, R.; Richter, S.; Ebbinghaus, S.G.; Lorenz, M.; Bundesmann, C.; Grundmann, M.
    We present optical properties in the near-infrared to vacuum-ultraviolet spectral range of hexagonal YMnO3. The high-quality (110)-oriented bulk single crystal was grown by the optical floating zone technique. We have determined the tensor of the dielectric function by means of Mueller matrix ellipsometry in the wide spectral range (0.5-9.15) eV. For the spectral range below 5.4 eV, we present much more precise data compared to previous reports. For higher energies no experimental reports were given previously. The experimental dielectric function of YMnO3 agrees generally with theoretical calculations. We found the well known transitions involving hybridized oxygen-Mn states and Mn-3d states to be spectrally localized with a homogeneous Lorentzian lineshape. At energies above these transitions, we observe pseudo-transparent points where for each of the principal diagonal elements of the dielectric function tensor the imaginary part approaches zero but at different photon energies. These are followed at the onset of the high-absorption spectral range by parabolic direct band-band transitions which have not been reported so far.