We report 17O NMR measurements in a single crystal of NpO2. We have observed oscillatory spin-echo decay for certain O sites below T0 = 26 K. These spin-echo oscillations are well understood in terms of an axially symmetric electric field gradient created by a longitudinal triple-q antiferro-quadrupolar ordering. In the present work, we show that direct observation of the quadrupolar order parameters is possible by means of NMR.
- Multipolar order
- Spin-echo oscillation
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics