Electrodynamics of Charge Carriers of Negative Effective Mass in Crystals

The transport properties of negative-effective-mass carriers in crystals are studied. The electrical conductivity of a sample in which the electron distribution function is weakly-perturbed from its thermal equilibrium value is always positive, even in the presence of a magnetic field. Therefore, cyclotron resonance experiments in equilibrium should display energy absorption, although the negative-mass carriers will circulate in the sense opposite to that of positive-mass carriers of the same charge.