2012/04/30 by M. E. Zhitomirsky, M. V. Gvozdikova, P. C. W. Holdsworth +2 · 8 citations
Earth and Planetary Sciences · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Bioinformatics #Condensed matter physics #Degeneracy (biology) #Inelastic neutron scattering #Neutron scattering #Nuclear materials and radiation effects #Order (exchange) #Physics #Pyrochlore #Quantum #Quantum computer #Quantum fluctuation #Quantum mechanics #Scattering #Spin (aerodynamics) #cond-mat.stat-mech #cond-mat.str-el #earthquake and tectonic studies
paper · pdf · doi:10.1103/physrevlett.109.077204
published as Phys. Rev. Lett. 109, 077204 (2012) · 5 pages, 4 figures, final version
arxiv created 2012/05/28 · openalex publication_date 2012/08/16 · arxiv updated 2012/08/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Motivated by recent neutron scattering experiments, we derive and study an effective "pseudodipolar" spin-1/2 model for the XY pyrochlore antiferromagnet Er(2)Ti(2)O(7). 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 noncoplanar 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.