Phonon Dynamics and Multipolar Isomorphic Transition in beta-pyrochlore KOs2O6
arXiv:1101.0647 · doi:10.1143/JPSJ.80.023714
Abstract
We investigate with a microscopic model anharmonic K-cation oscillation observed by neutron experiments in beta-pyrochlore superconductor KOs2O6, which also shows a mysterious first-order structural transition at Tp=7.5 K. We have identified a set of microscopic model parameters that successfully reproduce the observed temperature dependence and the superconducting transition temperature. Considering changes in the parameters at Tp, we can explain puzzling experimental results about electron-phonon coupling and neutron data. Our analysis demonstrates that the first-order transition is multipolar transition driven by the octupolar component of K-cation oscillations. The octupole moment does not change the symmetry and is characteristic to noncentrosymmetric K-cation potential.
5 pages, 4 figures, submitted to J. Phys. Soc. Jpn
References in corpus (8)
- Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6
- NMR relaxation and resistivity from rattling phonons in pyrochlore superconductors
- Rattling-Induced Superconductiviy in the Beta-Pyrochlore Oxides AOs2O6
- Mass enhancement, correlations, and strong coupling superconductivity in the beta-pyrochlore KOs2O6
- NMR Observation of Rattling Phonons in the Pyrochlore Superconductor KOs2O6
- Thermal Conductivity of the Pyrochlore Superconductor KOs2O6: Strong Electron Correlations and Fully Gapped Superconductivity
- Neutron Scattering Study of the Localized Mode in the beta-Pyrochlore Superconductors AOs2O6
- A Possible Phase Transition in beta-pyrochlore Compounds