Abstract
CePtSi2 was reported to exhibit an antiferromagnetic order below T∗=1.8 K at ambient pressure, a valence state change at ∼1.2 GPa, and superconductivity in the range between 1.4 and 2.1 GPa with a maximum transition temperature of 0.14 K [T. Nakano, Phys. Rev. B 79, 172507 (2009)1098-012110.1103/PhysRevB.79.172507]. We have performed polycrystalline and single-crystal neutron diffraction experiments to determine the magnetic structure under ambient and high pressures. We found incommensurate magnetic peaks with a magnetic propagation vector of (0.32,0,0.11) at ambient pressure below TSDW∼1.25 K. Those magnetic peaks originate from a spin-density-wave order with the easy axis along the c axis and an averaged ordered moment of 0.45(5)μB, suggesting that there may be an intermediate phase between T∗ and TSDW. Applying pressures, the magnetic propagation vector shows no change and the magnetic order disappears around 1.0 GPa, which is much lower than the critical pressure for the superconducting phase. The results suggest that other than magnetic fluctuations may play a primary role in the superconducting pairing mechanism.
| Original language | English |
|---|---|
| Article number | 245111 |
| Journal | Physical Review B |
| Volume | 105 |
| Issue number | 24 |
| DOIs | |
| State | Published - Jun 15 2022 |
Funding
We thank R. Kobayashi for his preliminary measurement at the early stage of this research. This research was supported in part by the U.S.-Japan Cooperative Program on Neutron Scattering. This research used resource at the Spallation Neutron Source and High Flux Isotope Reactor, U.S. DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. This work was partially supported by MEXT, the Grant-in-Aid for Scientific Research “Grant No. 19H00648.”