Coexistence of bandlike and localized 5f electrons in UxLa1-xS -: art. no. 184408

The optical and magneto-optical properties of UxLa1-xS single crystals have been studied for different uranium concentrations x. The infrared optical properties reveal a rapid increase of the free-carrier effective mass even at low x, which can be assigned to an admixture of 5f character to the conduction band. The magneto-optical Kerr spectrum of U0.8La0.2S can be interpreted by the interplay of an optical enhancement effect and interband contributions, which have not been observed in our former study of U0.55La0.45S, i.e., for lower U concentration. The combination of the optical and magneto-optical data leads to a picture with both localized and itinerant contributions of the 5f electrons of uranium. Superconducting quantum interference device magnetometry has been used to investigate magnetic ordering temperatures. Magnetic ordering has been found down to x=0.4 with a reduced magnetocrystalline anisotropy in the middle concentration range.