We report nuclear quadrupole resonance (NQR) studies on Ru-sites of filled skutterudite compounds R Ru4 P12 (R = La, Nd, Sm) in zero magnetic field. For NdRu4 P12, the 101Ru-NQR signal disappears below TC = 1.6 K, which is indicative of the transformation into the ferromagnetically ordered ground state. For SmRu4 P12, a single 101Ru-NQR line splits into two lines below the metal-insulator transition temperature TMI = 16.5 K with the intensity ratio of 3 : 1. This result gives evidence that there are two inequivalent Ru-sites with different electric field gradient. The intensity ratio leads to a conclusion that the symmetry is lowered below TMI from a cubic Im over(3, -) space group to a trigonal R over(3, -) one.
- Filled skutterudite
- Metal-insulator transition
- SmRu P
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering