High-field cooperative transport phenomena and screening in phase-separated degenerate antiferromagnetic semiconductors

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