69Ga NMR spectra are reported and analyzed for the paramagnetic and antiferromagnetic (AFM) ordered states of UGa3(TN=67 K). Ordered-state splitting of the NMR lines indicates that the fourfold symmetry of the Ga-site hyperfine (HF) coupling is broken in the AFM state. A striking change in the Ga HF coupling constant also occurs at TN. These effects are attributed to uranium (5f) orbital ordering, which appears to set in just below TN. Orientation of the U moments has been determined as [11δ](0<δ<1) for 40 K<T<TN and [α,β,γ] (α,β,γ≠) for T<40 K. Electric-field gradients and field-dependent HF effects are also discussed.
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2002 Dec 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics