Neutron scattering observations on the magnetic phases of rareearth ternary superconductors

Abstract

A number of ternary compounds become superconducting even though they contain a chemically ordered sublattice of magnetic rare-earth ions. Studies of the physical properties of these materials have revealed anomalies below T/sub c/ which have been attributed to magentic ordering transitions. Usng neutron spectrometers at the Brookhaven National Laboratory, a group of us has demonstrated that simple magnetic structures with long-range order do occur, and we have solved some of the magnetic structures of these superconductors. Specifically, we have found that in DyMo/sub 6/S/sub 8/ and TbMo/sub 6/S/sub 8/ an antiferromagnetic structure coexists with superconductivity. In two other compounds, ErRh/sub 4/B/sub 4/ and HoMo/sub 6/S/sub 8/ we have found that the development of ferromagnetism is responsible for the quenching of superconductivity. A study of the critical magnetic neutron scattering near the superconducting ..-->.. ferromagnetic transitions shows the presence of fluctuations into a state with an oscillatory magnetization of wave length lambda = 100A.