Giant magnetoresistance of magnetic semiconductor heterojunctions

The giant magnetoresistance characteristics of magnetic III-V semiconductor p-n heterojunctions are described. The origin of the extremely large positive magnetoresistance (2680%) observed at room temperature and at a field of 18 T is attributed to efficient spin-polarized carrier transport. The magnetocurrent ratio of the junction saturates with magnetic field. The field dependence of the magnetoresistance points to the existence of a paramagnetic component, which determines the degree of spin polarization of the junction current. This work indicates that highly spin-polarized magnetic semiconductor heterojunction devices that operate at room temperature can be realized.