HIGH-FIELD COOPERATIVE TRANSPORT PHENOMENA AND SCREENING IN PHASE-SEPARATED DEGENERATE ANTIFERROMAGNETIC SEMICONDUCTORS

Response to a strong electric field is investigated of degenerate anti ferromagnetic semiconductors EuTe spontaneously separated into antifer romagnetic and ferromagnetic phases. Whereas in weak fields their resp onse is Ohmic, in strong fields a sequence of very high peaks appears over the Ohmic-type background beginning from a certain threshold fiel d strength. Their spacing decreases with increasing field strength. Th ese peaks are explained by cooperative motion of charged ferromagnetic microregions inside the antiferromagnetic host. The screening by thes e microregions is investigated theoretically.