Insulator-metal transition in HgTe in crossed magnetic and electric fields

Abstract

Zero-gap semiconductor HgTe in the presence of crossed magnetic and electric fields is considered theoretically. An external magnetic field opens an energy gap between the Landau levels in the conduction and the heavy-hole valence bands. An electric field in the crossed-field configuration closes this gap, inducing an insulator-metal transition at low temperatures. The structure of Landau levels in HgTe in crossed fields has been calculated. In order to decide whether the gap really closes, the authors have also calculated the kz dependence of the Landau subbands. For B=2 T the insulator-metal transition occurs at E approximately=0.98 kV cm-1. It is shown that the insulator-metal transition is preceded by tunnelling effects.