Effect of randomness on anomalous Hall coefficient in antiferromagnet U2PdGa3

The Hall effect has been studied for antiferromagnet U2PdGa3. In the paramagnetic state, the Hall data can be interpreted in terms of skew scattering theory for heavy-fermion systems. We observe a large contribution of anomalous Hall coefficient, indicating a dominated contribution of incoherent skew scattering by uranium 5f moments. Interesting behaviour of the RH(T) dependence is found at low temperatures. The RH(T) curve displays a plateau between T* = 12 and TN = 33 K, followed by a shoulder with further decreasing temperature. The appearance of the anomaly around T* suggests the existence of a new scattering mechanism, in addition to well known skew and jump-side scatterings. We compare the Hall data of U2PdGa3 with those observed for strongly correlated electron systems and with those of spin-glasses. Like the latter systems, non-zero spin chirality seems to play a considerable role in the anomalous Hall effect of U2PdGa3.