29Si NMR and magnetic susceptibility of U3Si2

The magnetic susceptibility, χm, of U3Si2 has been measured in the temperature range 4-1000 K. It exhibits a broad maximum (Tmax ≅ 300 K) which may relate to the spin fluctuation process. Below Tmax the microscopic magnetic properties of U3Si2 have been investigated by the 29Si Knight shift (K) and spin-lattice relaxation rate (1/T1). The Knight shift versus susceptibility relation gives a hyperfine coupling constant Hhf = 48 kOe/μB. From the extrapolated limit of the linear K vs χm curve a large positive temperature-independent contribution to χm is obtained. This is attributable to the Van Vleck-type orbital paramagnetism, to be expected in metals with unfilled degenerate bands. The temperature dependencies of χm, K and (1/T1) give evidence for the fluctuations of the uranium 5f moments. The characteristic fluctuation rate is ∼3kBTmax/hwhen an effective number of uranium ions involved in the transferred hyperfine interaction is limited to first neighbours. (orig.)