Determination of the muon site in URh2Ge2

As-grown single crystals of the compound URh2Ge2 have been shown by tnagnet ic and mu SR measurements to exhibit a spin-glass ground state below a temp erature of 10 K. The rapid decay of the muon polarization below the freezin g temperature was found to be isotropic, whereas anisotropic relaxation may be expected (depending on the muon site) if the U-ion magnetic moment were aligned along the c-axis. We measured the dependence of transverse-field m uon shifts and line widths on temperature and magnetic field orientation. B ased on our results, the muon site is (1/2,0,0.1). Simulations of the muon decay signal for random and Ising (c-axis aligned) spin-glass states indica te that the Ising case should have led to anisotropic behaviour of the deca y. The experimentally observed isotropic polarization decay thus strongly s uggests a random anisotropy for U moments in UR2Ge2. (C) 2000 Elsevier Scie nce B.V. All rights reserved.