ELECTRONIC-STRUCTURE OF URHSI

URhSi crystallizes in the orthorhombic TiNiSi-type of structure and or ders ferromagnetically below 9.5 K. The enhanced C-p/T value extrapola ted to zero kelvin (186 mJ mol(-1) K-2) which can be partially reduced in magnetic fields (147 mJ mol(-1) K-2 at 5T) indicates a considerabl e magnetic contribution to the specific heat even at very low temperat ures. Magnetization data points to a strong magnetocrystalline anisotr opy. The best fit of a powder neutron diffraction data at low temperat ures is obtained for a ferromagnetic model with U-moments of 0.11 mu(B ) along the c-axis. These results classify URhSi as an itinerant 5f-el ectron ferromagnet with strongly reduced U magnetic moments. Electroni c-structure calculations were performed using the optimized LCAO metho d in the local density approximation. The 5f-states of U were treated as band states. U magnetic moment of 0.09 mu(B) and a magnetocrystalli ne anisotropy energy (E-c-E-a) = -59 meV has been obtained from fully relativistic spin-polarised calculations including orbital polarizatio n enhancement. (C) 1997 Elsevier Science Ltd.