DyNi2Mn—magnetisation and Mössbauer spectroscopy
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The physical properties of DyNi2Mn doped with 57Fe have been investigated by X-ray diffraction, magnetisation (10–300 K) and 57Fe Mössbauer spectroscopy measurements (5–300 K). DyNi2Mn(57Fe) crystallizes in the MgCu2-type cubic structure (Fd −3m space group). The ordering temperature is found to be TC = 99(2) K, much higher than those of DyNi2 (∼22 K) and DyMn2 (∼35 K). Analyses of isothermal M–H curves and the related Arrott plots confirm that the magnetic phase transition at TC is second order. The magnetic entropy change around TC is 4.0 J/kg K for a magnetic field change of 0 T to 5 T. The spectra above TC exhibit features consistent with quadrupolar effects while below TC the spectra exhibit magnetic hyperfine splitting. The Debye temperature for DyNi2Mn has been determined as θD = 200(20) K from a fit to the variable temperature isomer shift IS(T).
KeywordsPhase transition Mössbauer spectroscopy Magnetic entropy change
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