Neutron scattering study on high-quality single crystals of non-centrosymmetric heavy-fermion superconductor CePtSi

高純度単結晶を用いた空間反転対称性の欠如した重い電子系超伝導体CePtSiの中性子散乱

金子 耕士   ; Stockert, O.*; Skoulatos, M.*; Schneidewind, A.*; 竹内 徹也*; 松田 達磨; 芳賀 芳範   ; 摂待 力生*; 大貫 惇睦; 目時 直人   

Kaneko, Koji; Stockert, O.*; Skoulatos, M.*; Schneidewind, A.*; Takeuchi, Tetsuya*; Matsuda, Tatsuma; Haga, Yoshinori; Settai, Rikio*; Onuki, Yoshichika; Metoki, Naoto

The discovery of heavy-fermion superconductivity in non-centrosymmetric compound CePtSi, and subsequent findings of Ce (T: transition metal, X: Si, Ge) bring a new essence in the condensed matter physics, since a novel type of superconducting properties is expected to come out. In CePtSi, the compound shows an antiferromagnetic (AFM) order at =2.2 K and enters into a heavy-fermion superconducting state below 0.5 K. Through neutron scattering experiments under external magnetic field, we identified anomalous field response in CePtSi in the AFM state; AFM intensity showed enormous enhancement with increasing an applied field. The intensity kept increasing up to 7 T with the kink at around the additional phase boundary. These features suggest that the magnetic order in CePtSi is not a simple AFM one, and imply that large fraction of magnetic response could be still missing in this compound.