Large magnetoresistance in an inhomogeneous magnetic semiconductor

A new way of attaining large values of magnetoresistance in a magnetic semi conductor was investigated. The mechanism of magnetoresistance is based on the formation of a space charge, a depletion layer, and a contact potential U-c at the interface between two semiconductors with different Fermi level s E-n(F) and E-p(f) and on the dependence of U-c, the electrical resistivit y, and the size of the depletion layer in the magnetic semiconductor on the magnetic field strength. The model proposed was experimentally verified us ing a microstructure consisting of an HgCr2Se4 n-layer with a thickness of up to several tens of microns deposited on the surface of a bulk p-HgCr2Se4 single crystal. Depending on microstructure parameters, a sharp (up to sim ilar to 30 times) rise in the current flowing through the n-layer was obser ved in the region of Curie temperature upon switching on a magnetic field ( H similar to 15 kOe). (C) 2000 MAIK "Nauka/Interperiodica".