88 research outputs found

    Magnetic dichroism study on Mn1.8_{1.8}Co1.2_{1.2}Ga thin film using a combination of X-ray absorption and photoemission spectroscopy

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    Using circularly polarised radiation and a combination of bulk-sensitive hard X-ray photoelectron spectroscopy and X-ray-absorption spectroscopy (XAS) we studied the electronic and magnetic structure of epitaxial Mn1.8_{1.8}Co1.2_{1.2}Ga thin films. Spin resolved Bloch spectral functions, density of states as well as charge and magnetisation densities were investigated by a first-principles analysis of full potential, fully relativistic Korringa--Kohn--Rostoker calculations of the electronic structure. The valence states were experimentally investigated by using linear dichroism in the angular distribution and comparing the results to spin-resolved densities of states. The linear dichroism in the valence band enabled a symmetry analysis of the contributing states. The spectra were in good agreement with the theoretical partial density of states. The element-specific, spin-resolved, unoccupied densities of states for Co and Mn were analysed by using XAS and X-ray magnetic circular dichroism (XMCD) at the L3,2L_{3,2} edges. The spectra were influenced by strong correlation effects. XMCD was used to extract the site resolved magnetic moments. The experimental values of mMn=0.7μBm_{\rm Mn}=0.7\:\mu_B and mCo=1.05μBm_{\rm Co}=1.05\:\mu_B agree very well with the calculated magnetic moments. Magnetic circular dichroism in angle-resolved photoelectron spectroscopy at the Mn and Co 2p2p core level exhibited a pronounced magnetic dichroism and confirmed the localised character of the Mn dd valence states

    Magnetic and transport properties of tetragonal- or cubic-Heusler-type Co-substituted Mn-Ga epitaxial thin films

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    The composition dependence of the structural, magnetic, and transport properties of epitaxially grown Mn-Co-Ga films were investigated. The crystal structure was observed to change from tetragonal to cubic as the Co content was increased. In terms of the dependence of saturation magnetization on the Co content, relatively small value was obtained for the Mn2.3_{2.3}Co0.4_{0.4}Ga1.3_{1.3} film at a large {\it K}u_\textrm u value of 9.2 Merg/cm3^3. Electrical resistivity of Mn-Co-Ga films was larger than that of pure Mn-Ga film. The maximum value of the resistivity was 490 μΩ\mu\Omegacm for Mn2.2_{2.2}Co0.6_{0.6}Ga1.2_{1.2} film. The high resistivity of Mn-Co-Ga might be due to the presence of localized electron states in the films due to chemical disordering caused by the Co substitution.Comment: 3 pages, 5 figures. The article has been submitted to the Journal of Applied Physics as a Proceedings for the 12th Joint MMM/INTERMAG conferenc

    Perpendicularly magnetized Mn-Co-Ga-based thin films with high coercive field

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    Mn3x_{3-x}Cox_{x}Ga epitaxial thin films were grown on MgO substrates by magnetron co-sputtering. Structures were tetragonal or cubic depending on Co content. Composition dependence of saturation magnetization and uniaxial magnetic anisotropy KuK_u of the films were investigated. A high KuK_u (1.2 MJ m3^{-3}) was achieved for the Mn2.6_{2.6}Co0.3_{0.3}Ga1.1_{1.1} film with the magnetic moment 0.84μB\mu_B. Valence band spectra were obtained by hard X-ray photoelectron spectroscopy. Sharp peaks in the cubic case, which were absent in the tetragonal case, prove that a van Hove singularity causes a band Jahn-Teller effect with tetragonal distortion. Observations agree well with the first-principles calculations

    Micro Scanning Laser Range Sensor for Planetary Exploration

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    This paper proposes a new type of scanning laser range sensor for planetary exploration. The proposed sensor has advantages of small size, light weight, and low power consumption with the help of micro electrical mechanical systems technology. We are in the process of developing a miniature two dimensional optical sensor which is driven by a piezoelectric actuator. In this paper, we present the mechanisms and system concept of a micro scanning laser range sensor
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