Magnetotransport Properties of La(Fe1-xSix)13 Compounds

Ternary La(Fe1-xSix)13 compounds undergo a first-order magnetic transition at the Curie temperature TC. Above TC, the compounds exhibit the itinerant electron metamagnetism. We have studied Hall effect and thermal conductivity of La(Fe1-xSix)13. The Hall resistivity was measured as a function of the magnetic field B at various temperatures. Using the magnetization data, we separated the normal Hall effect (NHE) and the anomalous Hall effect (AHE) in the ferromagnetic state. It is found that NHE is positive at low temperatures, while it becomes negative near TC. The large AHE was observed for x = 0.12. Our analyses revealed that the skew scattering is dominant in the AHE. The temperature dependence of thermal conductivity lambda exhibits a peak at TC for x = 0.12 and 0.14, while abrupt reduction in lambda was observed at TC for x = 0.10 both on cooling and on heating. We discuss the physical origins of these anomalies in the transport properties of La(Fe1-xSix)13.