FROZEN-IN DEVILS STAIRCASE IN U(RU1-XRHX)2SI2 MIXED COMPOUND SYSTEM AS STUDIED BY NEUTRON-DIFFRACTION

We have carried out neutron diffraction experiments in order to study on the intermediate phase of the mixed system, U(Ru1-xRhx)2Si2, of URu 2Si2 and URh2Si2, which are a heavy Fermion and a localized f-electron compounds, respectively. In the intermediate phase, the magnetic mome nt of the uranium atom has a normal magnitude but the ground state has a complex multi-Q-domain structure. The origin of this state is discu ssed on the basis of competing anisotropic interactions and randomness in them. An energy-based consideration is given to understand the var iation of the magnetic structures in U(Ru1-xRhx)2Si2 and Ce(Ru1-xRhx)2 Si2 sytems.