Pr magnetic order and spin dynamics in the cuprates

Magnetic neutron scattering measurements are reviewed for PrBa2Cu3O6+x and compared to related materials that contain Pr. In these materials the magne tic rare earth ordering temperatures are typically an order-of-magnitude hi gher than for the other rare earths, indicating that exchange interactions dominate the energetics of the magnetic system. For the spin dynamics in Pr 123, the strong f-electron hybridization produces non-Fermi liquid-like sca ttering, which appears to destroy any chance for superconductivity. This be havior contrasts strongly with the sharp crystal field excitations found fo r the heavy rare earths, as well as with the sharp levels found in other Pr systems.