Browsing by Author "Toth, S"

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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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    Magnetic soft modes in the distorted triangular antiferromagnet alpha-CaCr(2)O(4)
    (American Physical Society, 2012-09-19) Toth, S; Lake, B; Hradil, K; Guidi, T; Rule, KC; Stone, MB; Islam, ATMN
    In this Letter, we explore the phase diagram and excitations of a distorted triangular lattice anti-ferromagnet. The unique two-dimensional distortion considered here is very different from the "isosceles''- type distortion that has been extensively investigated. We show that it is able to stabilize a 120 degrees spin structure for a large range of exchange interaction values, while new structures are found for extreme distortions. A physical realization of this model is alpha-CaCr(2)O(4), which has a 120 degrees structure but lies very close to the phase boundary. This is verified by inelastic neutron scattering which reveals unusual rotonlike minima at reciprocal space points different from those corresponding to the magnetic order. © 2012 The American Physical Society
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    Magnetic soft modes in the distorted triangular antiferromagnet α-CaCr2O4
    (American Physical Society, 2012-09-19) Toth, S; Lake, B; Hradil, K; Guidi, T; Rule, KC; Stone, MB; Islam, ATMN
    In this Letter, we explore the phase diagram and excitations of a distorted triangular lattice anti-ferromagnet. The unique two-dimensional distortion considered here is very different from the "isosceles''- type distortion that has been extensively investigated. We show that it is able to stabilize a 120 degrees spin structure for a large range of exchange interaction values, while new structures are found for extreme distortions. A physical realization of this model is alpha-CaCr2O4, which has a 120 degrees structure but lies very close to the phase boundary. This is verified by inelastic neutron scattering which reveals unusual rotonlike minima at reciprocal space points different from those corresponding to the magnetic order. © 2012, American Physical Society.