Magnetotransport properties in the noncentrosymmetric itinerant ferromagnet Cr₁₁Ge₁₉

We have investigated the anomalous Hall effect and magnetoresistance of the noncentrosymmetric itinerant ferromagnet Cr₁₁Ge₁₉. We have found a characteristic temperature (∼30 K) below the ferromagnetic transition temperature T_C = 85 K. While a conventional anomalous Hall conductivity that is proportional to the magnetization smoothly grows below T_C, the anomalous Hall conductivity shows an additional enhancement below the characteristic temperature. Concomitantly, the AMR emerges and the magnitude of negative magnetoresistance begins to increase toward low temperature. Because there is no anomaly in the temperature dependence of magnetization around the characteristic temperature, the origin of these observations in transport properties is ascribed to some electronic structure with the energy scale of 30 K. We speculate this is caused by the spin splitting due to breaking of spatial inversion symmetry.