Thermal difference reflectivity of tilted 2D Dirac systems

We investigate the thermal derivative spectra of the optical reflectivity from massive tilted Dirac systems. The density of states and temperature dependence of the chemical potential are obtained as previous steps to calculate the optical conductivity tensor at finite temperature through a thermal convolution. Changes in reflection caused by variations of temperature allow a sharp identification of critical frequencies of the optical response. These spectral features in the thermoderivative spectrum allow in turn the determination of energy gaps and tilting of the band structure. Comparison between the spectra of several low-energy Dirac Hamiltonians is presented. The results suggest that thermal difference spectroscopy might be a useful technique to probe interband transitions of 2D Dirac fermions.