Ground-state magnetic structure of CeRh2Si2 and the response to hydrostatic pressure as studied by neutron diffraction

Neutron-diffraction experiments under high pressure have been done to study the magnetic structure of the ground state and the nature of the magnetic order of the pressure-induced superconductor CeRh2Si2. Two models for the magnetic structure of the ground state, namely, a 4-q superposed structure and a multidomain structure, have been tested and the former was found to be more realistic, though both of them have some inconsistency with the results of the previous NMR experiment. The pressure dependence of both the transition temperature and magnitude of the ordered magnetic moment indicate that the magnetism of this compound is basically itinerant despite its high transition temperature. Our studies also revealed that, when the pressure is close to the critical magnitude to destroy the antiferromagnetism, the compound can have a "tiny ordered moment" which is widely observed in the metallic Kondo-lattice compounds.