Claudia Decorse

Spin liquid correlations, anisotropic exchange, and symmetry breaking in Tb2Ti2O7

We have studied the low energy spin dynamics between 4.6K and 0.07K in a Tb2Ti2O7 single crystal sample, by means of inelastic neutron scattering experiments. The spectra consist in a dual response, with a static and an inelastic contribution, showing striking Q-dependences. We propose an interpretation involving an anisotropic exchange interaction in combination with a breaking of the threefold symmetry at the rare earth site. Simulations of the Q-dependent scattering in the Random Phase Approximation account well for the inelastic response.

Spin dynamics in the presence of competing ferromagnetic and antiferromagnetic correlations in Yb2Ti2O7

In this work, we show that the zero field excitation spectra in the quantum spin ice candidate pyrochlore compound \ybti\ is a continuum characterized by a very broad and almost flat dynamical response which extends up to

Field evolution of the magnetic structures in Er2Ti2O7 through the critical point

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Double vibronic process in the quantum spin ice candidate Tb2Ti2O7 revealed by terahertz spectroscopy

meV, coexisting or not with a quasi-elastic response depending on the wave-vector. The spectra do not evolve between 50 mK and 2 K, indicating that the spin dynamics is only little affected by the temperature in both the short-range correlated and ordered regimes. Although classical spin dynamics simulations qualitatively capture some of the experimental observations, we show that they fail to reproduce this broad continuum. In particular, the simulations predict an energy scale twice smaller than the experimental observations. This analysis is based on a careful determination of the exchange couplings, able to reproduce both the zero field diffuse scattering and the spin wave spectrum rising in the field polarized state. According to this analysis, \ybti\ lies at the border between a ferro and an antiferromagnetic phase. These results suggest that the unconventional ground state of \ybti\ is governed by strong quantum fluctuations arising from the competition between those phases. The observed spectra may correspond to a continuum of deconfined spinons as expected in quantum spin liquids.

Antiferroquadrupolar correlations in the quantum spin ice candidate Pr2Zr2O7

We have measured neutron-diffraction patterns in a single-crystal sample of the pyrochlore compound Er{sub 2}Ti{sub 2}O{sub 7} in the antiferromagnetic phase (T=0.3 K), as a function of the magnetic field, up to 6 T, applied along the [110] direction. We determine all the characteristics of the magnetic structure throughout the critical point at H{sub c}=2 T. As a main result, all Er moments align along the field at H{sub c} and their values reach a minimum. Using a four-sublattice self-consistent calculation, we show that the evolution of the magnetic structure and the value of the critical field are rather well reproduced using the same anisotropic exchange tensor as that accounting for the local paramagnetic susceptibility. In contrast, an isotropic exchange tensor does not yield the correct moment variations through the critical point. The model also accounts semiquantitatively for other experimental data obtained in previous works, such as the field dependence of the heat capacity, energy of the dispersionless inelastic modes and transition temperature.

Mesoscopic correlations in Tb2Ti2O7 spin liquid

The origin of quantum fluctuations responsible for the spin liquid state in Tb

Field-induced phase diagram of the XY pyrochlore antiferromagnet Er2Ti2O7

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Ising versus XY anisotropy in frustrated R(2)Ti(2)O(7) compounds as "Seen" by Polarized Neutrons.

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Structural Investigation and Functional Properties of MgxNi1−xFe2O4 Ferrites

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Anisotropic propagating excitations and quadrupolar effects in Tb2Ti2O7.

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