Abstract
CeCoSi is an intermetallic antiferromagnet with a very unusual temperature-pressure phase diagram: At ambient pressure it orders below TN=8.8K, while application of hydrostatic pressure induces a new magnetically ordered phase with exceptionally high transition temperature of ∼40K at 1.5 GPa. We studied the magnetic properties and the pressure-induced magnetic phase of CeCoSi by means of elastic and inelastic neutron scattering (INS) and heat capacity measurements. At ambient pressure CeCoSi orders into a simple commensurate AFM structure with a reduced ordered moment of only mCe=0.37(6)μB. Specific heat and low-energy INS indicate a significant gap in the low-energy magnon excitation spectrum in the antiferromagnetic phase, with the CEF excitations located above 10 meV. Hydrostatic pressure gradually shifts the energy of the magnon band towards higher energies and the temperature dependence of the magnons measured at 1.5 GPa is consistent with the phase diagram. Moreover, the CEF excitations are also drastically modified under pressure.
| Original language | English |
|---|---|
| Journal | Physical Review B |
| Volume | 101 |
| Issue number | 21 |
| DOIs | |
| State | Published - Jun 1 2020 |
Funding
We acknowledge A. S. Sukhanov for stimulating discussions, C. Goodway for help with the high-pressure experiments at ISIS Neutron and Muon source, and K. A. Nikitina for assistance with the CEF analysis. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory. S.E.N. acknowledges support from the International Max Planck Research School for Chemistry and Physics of Quantum Materials (IMPRS-CPQM). D.G.F. and C.G. acknowledge support from the German Research Foundation (DFG) through Grant No. GE 602/4-1 and Fermi-NEst.