Third-harmonic generation in excitonic insulators
نویسندگان
چکیده
We study third-harmonic generation (THG) in an excitonic insulator (EI) described a two-band correlated electron model. Employing the perturbative expansion with respect to external electric field, we derive THG susceptibility taking into account collective dynamics of order parameter. In inversion-symmetric EI, parameter motion is activated at second field and its effects arise THG. find three peaks energies $\ensuremath{\hbar}\mathrm{\ensuremath{\Omega}}={\mathrm{\ensuremath{\Delta}}}_{g}/3$, ${\mathrm{\ensuremath{\Delta}}}_{g}/2$, ${\mathrm{\ensuremath{\Delta}}}_{g}$, where ${\mathrm{\ensuremath{\Delta}}}_{g}$ band gap. While response ${\mathrm{\ensuremath{\Delta}}}_{g}/3$ caused by bare three-photon excitation independent particle across gap, latter two involve order. The resulting resonant are prominent particular BCS regime but they become less significant BEC regime. demonstrate that peak originated observable temperature profile intensity. Our suggests measurement should be promising for detecting nature materials.
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ژورنال
عنوان ژورنال: Physical Review B
سال: 2021
ISSN: ['1098-0121', '1550-235X', '1538-4489']
DOI: https://doi.org/10.1103/physrevb.104.245103