Quantum dynamics in Pr2ScNbO7

We have studied the diffuse scattering from Pr2ScNbO7 using the D7 diffractometer at the ILL. We find the characteristic star-fish pattern of magnetic diffuse scattering characteristic of other Pr-based spin-ice materials has completely disappeared. The structural diffuse scattering suggests partial ordering of the cations on the pyrochlore B-sites so that there are two Sc3+ and two Nb5+ ions per tetrahedra, an arrangement known as charge ice, and this leads to a disordered strain field. These strains give effective local transverse fields, and this is predicted to lead to either a true quantum spin liquid or a paramagnetic phase. We now propose to measure the magnetic excitations at sub-Kelvin temperatures and at low energy transfers on LET at ISIS. The width of the spectrum in energy transfer will allow us to distinguish between paramagnetic scattering and quantum spin dynamics.