Electron correlation and disorder in Hg sub (1-x) Cd sub x Te in magnetic field.

We report both linear and non-linear magnetoconductance measurements on two different density samples of similar stoichiometry Hg sub (1-x) Cd sub x Te for 0.01 T 2.5K and 0 H 80 KOe. The critical magnetic field for driving the samples through the metal-insulator transition is proportional to temperature at low T and saturates at T ~ 2K, in quantitative agreement with a theory for the melting of a Wigner crystal in magnetic field. In the insulating state, we observe a non-Ohmic I- V characteristic at threshold electric fields less than 1 mV/cm. By analogy to theories for charge density wave depinning, we estimate that the electrons are correlated over regions of a few hundred lattice spacings.