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

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.