Transport Properties of the Metallic Two-dimensional Triangular Antiferromagnet Ag2CrO2

We have investigated the magnetotransport properties of polycrystalline samples of Ag2CrO2, which is a metallic two-dimensional triangular antiferromagnetic compound (TN ∼24 K). The electrical resistivity of this compound displayed metallic behavior and an abrupt decrease at TN. Below TN, almost linear positive magnetoresistance was observed. On the other hand, just above TN, a large negative magnetoresistance of -38% at 8 T was observed. The absolute value of the negative magnetoresistance decreases with increasing temperature. The Hall resistance showed a nonlinear behavior as a function of the magnetic field below TN. These results suggest that the transport properties of Ag2CrO2 are closely related to its unusual antiferromagnetic spin-structure.