Magnetic structure in the spin liquid Tb2Ti2O7induced by a [111] magnetic field: Search for a magnetization plateau

A. P. Sazonov, A. Gukasov, H. B. Cao, P. Bonville, E. Ressouche, C. Decorse, I. Mirebeau
2013 Physical Review B  
We have studied the field-induced magnetic structures of Tb 2 Ti 2 O 7 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 R3m, 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
more » ... , 3-out" spin structure (magnetic space group R3m ) 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.
doi:10.1103/physrevb.88.184428 fatcat:nbjtl7yy4janzf4szj4n2hqb7i