Magnetic structure in the spin liquid Tb 2 Ti 2 O 7 induced by a [111] magnetic field: Search for a magnetization plateau

Abstract : We have studied the field-induced magnetic structures of Tb2Ti2O7 pyrochlore by single-crystal neutron diffraction under a field applied along the [111] axis, up to H=12 T and down to T=40 mK. We refined the magnetic structures with k=0 propagation vector by performing a symmetry analysis in the space group R3¯m, reducing the number of free parameters to three only. The Tb moments gradually reorient towards the field direction, keeping close to a “3-in, 1-out / 1-in, 3-out” spin structure (magnetic space group R3¯m') in the whole measured field range 0.05-12 T. Our results rule out the “all-in/all-out” structure previously proposed and do not support the existence of a magnetization plateau. We perform a quantitative comparison with mean-field calculations and we propose the presence of a low-temperature dynamic symmetry breaking of the local trigonal symmetry, akin to a dynamic Jahn-Teller effect, i.e., preserving the overall cubic symmetry. We discuss the possible origin of this off-diagonal mixing term in the crystal field Hamiltonian in terms of quadrupole-quadrupole interaction or magnetoelastic effects.
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Physical Review B : Condensed matter and materials physics, American Physical Society, 2013, 88 (18), pp.184428. 〈10.1103/PhysRevB.88.184428〉
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https://hal-cea.archives-ouvertes.fr/cea-01477949
Contributeur : Dominique Girard <>
Soumis le : lundi 27 février 2017 - 17:41:58
Dernière modification le : lundi 24 septembre 2018 - 10:56:04

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A.P. Sazonov, A. Gukasov, H. B. Cao, P. Bonville, E. Ressouche, et al.. Magnetic structure in the spin liquid Tb 2 Ti 2 O 7 induced by a [111] magnetic field: Search for a magnetization plateau. Physical Review B : Condensed matter and materials physics, American Physical Society, 2013, 88 (18), pp.184428. 〈10.1103/PhysRevB.88.184428〉. 〈cea-01477949〉

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