MAGNETIC-ANISOTROPY IN UTX COMPOUNDS

We compare results of measurements of magnetization, specific heat, electrical resistivity and neutron diffraction on single crystals and oriented polycrystalline powders of various UTX compounds. Very strong anisotropy, persisting also in the paramagnetic state, is a general feature of these materials. Compounds with the hexagonal ZrNiAl-type structure exhibit, as a rule, a uniaxial anisotropy with an easy-magnetization direction along the c axis. Energies of the magnetic anisotropy (of the order of hundreds of kelvins) correlate with the expected development of hybridization strength within planes of the highest coordination of uranium atoms. As a result of this evidence the hybridization-mediated anisotropic exchange is tentatively assumed to be a source of the huge anisotropy. Particular symmetry of anisotropy reflects the type of arrangement of uranium atoms.