U-235 NMR study of antiferromagnet UO2

A typical hyperfine structure of U4+ ions is obtained by the U-235 NMR in t he antiferromagnetic state of UO2. The nuclear electric quadrupole interact ion indicates that the Sf-wave function in the cubic crystalline field is r educed to the axial symmetry below T-N. The nuclear spin-lattice relaxation rate at both uranium and oxygen sites shows a T-7-like behavior in the ant iferromagnetic state, which indicates the presence of a gapless spin-wave e xcitation. (C) 2000 Elsevier Science B.V. All rights reserved.