Abstract
The magnetically tuned insulator-metal transition in magnetic semiconductors is one of the most striking demonstrations of the interaction between localized magnetic moments and carriers.1 On the metallic side of the transition, it is believed that magnetotransport arises from electron-electron interactions in the presence of a giant Zeeman splitting of the conduction band. However, magnetotransport in the insulating phase is not well understood. The discovery of persistent photoconductivity in Cd1−xMnxTe:In2 has made it possible to control carrier concentration by illumination. This enables us to make transport measurements over a wide range of carrier concentrations in one single sample, ultimately leading to the phototuning of the Mott–Anderson transition in this magnetic semiconductor. In the present work, we report an investigation of magnetotransport and permittivity as a function of carrier concentration in Cd0.92Mn0.08Te:In(2×1018 cm−3). In the insulating phase, the resistivity shows an exp[(T0/T)1/2] temperature dependence, characteristic of variable range hopping in the presence of electron-electron interactions.3 Our results imply that magnetotransport is governed by local magnetization characteristic of the relevant length scale for the transport process.
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