Magnetic field induced localization transition in HgCdTe.

We have performed magnetoresistance and Hall resistance measurements on low carrier concentration n-type samples of Hg0.76Cd0.24Te at milliKelvin temperatures. We observe an abrupt rise in the Hall and magnetoresistance at a characteristic field H (c) which is a strong function of temperature and which allows us to reject magnetic freeze-out or localization by disorder as possible mechanisms. Instead, we propose that the magnetic field induces localization of the electrons into a three-dimensional Wigner lattice.