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arXiv · 1704.00176

Anomalous Anisotropic Exciton Temperature Dependence in Rutile TiO2

Edoardo Baldini·Adriel Dominguez·Letizia Chiodo·Evgeniia Sheveleva·Meghdad Yazdi-Rizi·Christian Bernhard·Angel Rubio·Majed Chergui
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Abstract

Elucidating the details of the electron-phonon coupling in semiconductors and insulators is a topic of pivotal interest, as it governs the transport mechanisms and is responsible for various phenomena such as spectral-weight transfers to phonon sidebands and self-trapping. Here, we investigate the influence of the electron-phonon interaction on the excitonic peaks of rutile TiO$_2$, revealing a strong anisotropic polarization dependence with increasing temperature, namely an anomalous blueshift for light polarized along the a-axis and a conventional redshift for light polarized along the c-axis. By employing many-body perturbation theory, we identify two terms in the electron-phonon interaction Hamiltonian that contribute to the anomalous blueshift of the a-axis exciton. Our approach paves the way to a complete ab initio treatment of the electron-phonon interaction and of its influence on the optical spectra of polar materials.

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Edoardo Baldini, Adriel Dominguez, Letizia Chiodo, Evgeniia Sheveleva, Meghdad Yazdi-Rizi, Christian Bernhard, Angel Rubio, Majed Chergui. 2017-04-01. Anomalous Anisotropic Exciton Temperature Dependence in Rutile TiO2. https://doi.org/10.1103/physrevb.96.041204

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