Polaronic signatures in mid-infrared spectra:  Prediction for ${\mathrm{LaMnO}}_3$ and ${\mathrm{CaMnO}}_3$

Hole-doped ${\mathrm{LaMnO}}_3$ and electron-doped ${\mathrm{CaMnO}}_3$ form self-trapped electronic states. The spectra of these states have been calculated using a two orbital (Mn $e_{\mathrm{g}}$ Jahn-Teller) model, from which the nonadiabatic optical conductivity spectra are obtained. In both cases the optical spectrum contains weight in the gap region, whose observation will indicate the self-trapped nature of the carrier states. The predicted spectra are proportional to the concentration of the doped carriers in the dilute regime, with coefficients calculated with no further model parameters.