Nonequilibrium electronic and structural Jahn-Teller dynamics in(NbSe4)3I

Abstract

Femtosecond time-resolved optical spectroscopy reveals complex nonequilibrium electronic and structural relaxation dynamics associated with an electronically driven Jahn-Teller (JT) structural phase transition at $274\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in the quasi-one-dimensional semiconductor ${(\mathrm{Nb}{\mathrm{Se}}_{4})}_{3}\mathrm{I}$. The relaxation dynamics of the electronic order parameter $\ensuremath{\eta}$ (associated with the JT transition) and accompanying structural relaxation are described using the Landau-Khalatnikov equation, and equations of motion for coupled phonons, respectively.