Thursday, October 11, 2012

1210.2787 (T. Kaneko et al.)

Orthorhombic-to-Monoclinic Phase Transition of Ta2NiSe5 Induced by the
Bose-Einstein Condensation of Excitons
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T. Kaneko, T. Toriyama, T. Konishi, Y. Ohta
Using the band structure calculation and mean-field analysis of the derived three-chain Hubbard model with phonon degrees of freedom, we discuss the origin of the orthorhombic-to-monoclinic phase transition of the layered chalcogenide Ta$_2$NiSe$_5$. We show that the Bose-Einstein condensation of excitonic electron-hole pairs cooperatively induces the instability of the phonon mode at momentum $q\rightarrow 0$ in the quasi-one-dimensional Ta-NiSe-Ta chain, resulting in the structural phase transition of the system. The calculated single-particle spectra reproduce the deformation of the band structure observed in the angle-resolved photoemission spectroscopy experiment.
View original: http://arxiv.org/abs/1210.2787

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