Magnetotransport Properties of CrO₂

Abstract

When conduction electrons are strongly coupled to core spins, as in double-exchange systems, they acquire a quantum (Berry) phase while moving through a crystal and are affected by a gauge field, with the result that they produce an anomalous Hall effect. We measured the transport properties of CrO₂ as a pure double-exchange ferromagnet, and show that the experimental results for the anomalous Hall effect of CrO₂ are consistent with this Berry phase mechanism caused by topological spin defects. We also discuss the possibility of magnetoresistance resulting from such defects.