Abstract
Field-orientation dependent specific heat C(H, θ) and the magnetization M(H, θ) have been measured on the Pr-based filled skutterudite compounds PrOs4Sb12 and PrFe 4P12. In PrOs4Sb12, fourfold angular oscillations of C(H, θ) have been observed in the normal state above the upper critical field Hc2 as well as in the vortex state. Field variation of the normal-state oscillation in C(H, θ) strongly suggests that antiferroquadrupolar fluctuations exist in the wide region above H c2. The oscillation exhibits a sign reversal below Hc2, whose origin is attributed to the nodal structure in which the superconducting gap takes minima (point nodes) along [100] directions. In PrFe4P 12, an exotic ordered phase (A-phase) below TA(H = 0)=6.5 K has been examined. Both M(H, θ) within the A-phase and TA(H, θ) show a smooth angular variation with a cubic anisotropy for H rotated in the (001) and (110) planes. The results strongly suggest that cubic symmetry is preserved in the A-phase; the order parameter is of Γ1 + type.
Original language | English |
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Pages (from-to) | 180-186 |
Number of pages | 7 |
Journal | Journal of the Physical Society of Japan |
Volume | 77 |
Issue number | SUPPL.A |
DOIs | |
State | Published - 2008 |
Keywords
- Gap structure
- Magnetization
- Multipole order
- Skutterudite
- Specific heat
- Unconventional superconductivity
ASJC Scopus subject areas
- General Physics and Astronomy