Abstract
The metal-insulator transition in n-type InP doped in excess of the Mott criterion has been induced by the application of a magnetic field. In the metallic regime the authors have investigated the corrections due to quantum interference and the electron-electron interaction. The interaction effect increases with decreasing temperature with a consequent reduction in the negative magnetoresistance. In the absence of the magnetic field the correction due to localisation dominates above 2.0K and that due to interactions below. Fields greater than 10T induce a metal-insulator transition which has been investigated down to 30 mK. A minimum metallic conductivity is found, in agreement with previous work at higher temperatures, and the activation energy varies linearly with magnetic field. A model is presented in which the magnetic field induces a transition from transport in a conduction band to an impurity band, in the impurity band the activation energy appears due to the separation of the two Hubbard bands.