Quantum order by disorder and accidental soft mode Er2Ti2O7
arXiv:1204.0595 · doi:10.1103/PhysRevLett.109.077204
Abstract
Motivated by recent neutron scattering experiments, we derive and study an effective "pseudo-dipolar" spin-1/2 model for the XY pyrochlore antiferromagnet Er2Ti2O7. While a bond-dependent in-plane exchange anisotropy removes any continuous symmetry, it does lead to a one-parameter `accidental' classical degeneracy. This degeneracy is lifted by quantum fluctuations in favor of the non-coplanar spin structure observed experimentally -- a rare experimental instance of quantum order by disorder. A non-Goldstone low-energy mode is present in the excitation spectrum in accordance with inelastic neutron scattering data. Our theory also resolves the puzzle of the experimentally observed continuous ordering transition, absent from previous models.
5 pages, 4 figures, final version
References in corpus (4)
- Dynamically-Induced Frustration as a Route to a Quantum Spin Ice State in Tb2Ti2O7 via Virtual Crystal Field Excitations and Quantum Many-Body Effects
- Structural distortion and the spin liquid state in Tb2Ti2O7
- Magnetic ordering in Gd2Sn2O7: the archetypal Heisenberg pyrochlore antiferromagnet
- Energetic selection of ordered states in a model of the Er2Ti2O7 frustrated pyrochlore XY antiferromagnet
Cited by in corpus (4)
- Definitive Evidence for Order-by-Quantum-Disorder in Er2Ti2O7
- Brownian Motion and Quantum Dynamics of Magnetic Monopoles in Spin Ice
- Magnetic order, magnetic correlations and spin dynamics in the pyrochlore antiferromagnet Er2Ti2O7
- Antiferromagnetic Spin Ice Correlations at (1/2,1/2,1/2) in the Ground State of the Pyrochlore Magnet Tb2Ti2O7