Browsing by Author "Evangelisti, M"

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    Magnetic structure and magnetocalorics of GdPO4
    (American Physical Society, 2014-10-21) Palacios, E; Rodríguez-Velamazán, JA; Evangelisti, M; McIntyre, GJ; Lorusso, G; Visser, D; de Jongh, LJ; Boatner, LA
    The magnetic ordering structure of GdPO 4 is determined at T=60 mK by the diffraction of hot neutrons with wavelength λ=0.4696 Å. It corresponds to a noncollinear antiferromagnetic arrangement of the Gd moments with propagation vector k=(1/2,0,1/2) . This arrangement is found to minimize the dipole-dipole interaction and the crystal-field anisotropy energy, the magnetic superexchange being much smaller. The intensity of the magnetic reflections decreases with increasing temperature and vanishes at T≈0.8 K, in agreement with the magnetic ordering temperature T N =0.77 K, as reported in previous works based on heat capacity and magnetic susceptibility measurements. The magnetocaloric parameters have been determined from heat capacity data at constant applied fields up to 7 T, as well as from isothermal magnetization data. The magnetocaloric effect, for a field change ΔB=0−7T , reaches −ΔS T =375.8mJ/cm 3 K −1 at T=2.1 K, largely exceeding the maximum values reported to date for Gd-based magnetic refrigerants.© 2014, American Physical Society.