Multiband Superconductivity in Filled-Skutterudite Compounds (Pr1-xLax)Os4Sb12: An Sb Nuclear-Quadrupole-Resonance Study
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- 15 December 2006
- journal article
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
- Vol. 75 (12)
Abstract
We report on the systematic evolution of normal-state properties and superconducting characteristics in filled-skutterudite compounds (Pr 1- x La x )Os 4 Sb 12 determined using Sb nuclear-quadrupole-resonance (NQR) experiments. The Sb-NQR spectra in these compounds have split into two sets, arising from different Sb 12 cages containing either Pr or La, which enables us to measure two kinds of nuclear spin–lattice relaxation time T 1 Pr and T 1 La . In the normal state, the temperature ( T ) dependence of 1/ T 1 Pr T showed almost the same behavior as that for pure PrOs 4 Sb 12 regardless of the increase in La content. In contrast, 1/ T 1 La T markedly decreases with increasing La concentration. These results show that 4 f 2 -derived magnetic fluctuations are almost localized at the Pr site. In the superconducting state for Pr-rich compounds of x =0.05 and 0.2, 1/ T 1 Pr exponentially decreases down to T =0.7 K with no coherence peak below T c as well as in PrOs 4 Sb 12 . A remarkable finding is that the r...Keywords
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