We report 73Ge-NQR studies on filled-skutterudite superconductors LaPt4Ge12 and PrPt4Ge 12 under zero external field. In PrPt4Ge12, the measurement of the nuclear spin-lattice relaxation rate 1/T1 has revealed a distinct coherence peak just below Tc followed by an exponential decrease well below Tc, evidencing that PrPt 4Ge12 is an s-wave superconductor with the isotropic gap in a weak-coupling regime. In LaPt4Ge12, the 1/T 1 exhibits the exponential decrease well below Tc, suggesting the isotropic s-wave superconductivity. Even though 73Ge-NQR-1/T1 in LaPt4Ge12 has been measured under zero field, its coherence peak was absent, which contrasts with the result in Pr-compound. This may point to a possible anisotropy in the Fermi surface and/or some damping effect of quasiparticles in association with electron-phonon interactions.
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Energy Engineering and Power Technology
- Electronic, Optical and Magnetic Materials