Large magnetoresistance in an inhomogeneous magnetic semiconductor

A new way of attaining large values of magnetoresistance in a magnetic semiconductor 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 levels E _n ^F and E _p ^f and on the dependence of U _c, the electrical resistivity, and the size of the depletion layer in the magnetic semiconductor on the magnetic field strength. The model proposed was experimentally verified using 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 ～30 times) rise in the current flowing through the n-layer was observed in the region of Curie temperature upon switching on a magnetic field (H～15 kOe).