MAGNETO-TRANSPORT ANOMALY IN SEMICONDUCTORS AT LOW CARRIER-DENSITIES, A WIGNER CONDENSATION

Transport properties of the narrow-gap semiconductors PbTe, PbSnTe, and HgCdTe were studied in the extreme magnetic quantum limit. With low carrier densities an anomalous behaviour was found for the longitudinal (ρ{variant}□) and the transverse (ρ{variant}⊥) magnetoresistance, for the Hall effect, and in the IU-characteristic. ρ{variant}□ increased near a critical magnetic field by almost two orders of magnitude. A pronounced kink in the ρ{variant}⊥ ∝ Bα dependence took place at the critical field. This critical magnetic field of the anomaly shows the features predicted for a Wigner condensation, i.e. the dependence on carrier density in all the three semiconductors. The new state at high magnetic fields is obviously a free carrier effect since it can be annihilated by heating the electrons in an electric field. © 1979.