Browsing by Author "Enderle, M"

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    Jahn-Teller versus quantum effects in the spin-orbital material LuVO 3
    (American Physical Society, 2015-04-13) Skoulatos, M; Toth, S; Roessli, B; Enderle, M; Habicht, K; Sheptyakov, D; Cervellino, A; Freeman, PG; Reehuis, M; Stunault, A; McIntyre, GJ; Tung, LD; Marjerrison, C; Pomjakushina, E; Brown, PJ; Khomskii, DI; Rüegg, A; Kreyssig, A; Goldman, AI; Goff, JP
    We report on combined neutron and resonant x-ray scattering results, identifying the nature of the spin-orbital ground state and magnetic excitations in LuVO3 as driven by the orbital parameter. In particular, we distinguish between models based on orbital-Peierls dimerization, taken as a signature of quantum effects in orbitals, and Jahn-Teller distortions, in favor of the latter. In order to solve this long-standing puzzle, polarized neutron beams were employed as a prerequisite in order to solve details of the magnetic structure, which allowed quantitative intensity analysis of extended magnetic-excitation data sets. The results of this detailed study enabled us to draw definite conclusions about the classical versus quantum behavior of orbitals in this system and to discard the previous claims about quantum effects dominating the orbital physics of LuVO3 and similar systems. © 2015 American Physical Society
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    The magnon dynamics and spin exchange parameters of FePS3
    (IOP Publishing Ltd, 2012-10-17) Wildes, AR; Rule, KC; Bewley, RI; Enderle, M; Hicks, TJ
    The spin waves in a powdered sample of a quasi-two-dimensional antiferromagnet, FePS(3), have been measured using neutron inelastic scattering. The data could be modelled and the exchange interactions determined using a two-dimensional Heisenberg Hamiltonian with single ion anisotropy. A suitable fit to the data could only be achieved by including magnetic interactions up to the third nearest neighbour, which is consistent with the findings for other members of the MPS(3) family (M = transition metal). The best fit parameters at 6 K were J(1) = 1.49 meV, J(2) = 0.04 meV, J(3) = -0.6 meV, with an anisotropy of Delta = 3.7 meV. Measurements as a function of temperature give a coarse measure of the behaviour of the anisotropy and the nature of the phase transition. © 2012, IOP Publishing LTD.