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Si金子 耕士
no journal, ,
The discovery of heavy-fermion superconductivity in the non-centrosymmetric compound CePtSi attracts a surge of interest due to possible appearance of a novel superconducting state under the lack of inversion symmetry. Another characteristics of superconductivity in CePtSi are its coexistence with a long-range antiferromagnetic order. Antiferromagnetic peaks persists deep inside the superconducting state. Distinct anomaly was observed neither in the magnetic order nor magnetic excitation spectra on passing through 
. On the other hand, our experiment revealed unusual magnetic field response near 
in CePtSi. An application of magnetic fields leads to strong enhancement in the antiferromagnetic intensity, opposite of what is observed in usual antiferromagnets. We will discuss details of our results.
Sb
Raymond, S.*; 桑原 慶太郎*; 金子 耕士
no journal, ,
PrOsSb is a Heavy Fermion (HF) superconductor (
= 1.85 K) that recently attracted a lot of attention due to the realization of strong interplay between electronic, multipolar and lattice properties and the related different possible mechanisms of electron pairing. Above 4 T, a Field Induced Ordered Phase (FIOP) occurs with a primar quadrupolar order parameter. The occurrence of an ordered phase in the vicinity of the superconducting pocket of the (H-T) phase diagram leads to the suggestion that quadrupolar fluctuations participate in the pairing by analogy with the scenario of magnetic mediated pairing for the Ce and U HF compounds. The observed magnetic excitation clearly softens at the wave-vector 
= (1, 0, 0), which is the same as the modulation vector of the FIOP and its intensity is smaller than that around the zone center. This results directly evidences that this excitonic behavior is derived mainly from non-magnetic quadrupolar interactions.