Spin Susceptibility Scaling in High-Temperature Superconductors

Science  19 Jun 1992:
Vol. 256, Issue 5064, pp. 1664-1667
DOI: 10.1126/science.256.5064.1664


The spin response of a nested Fermi surface represented by a tight binding energy band is found to exhibit scaling in frequency divided by temperature within a restricted regime close to half-filling of the band. Computations of the spin susceptibility reveal a surprising momentum variation at various temperatures and frequencies. Neutron scattering data on the high-temperature superconductor YBa2Cu3O6+x are analyzed for scaling near a momentum vector that spans nested regions of the orbit. Changes in the Fermi energy remove the scaling properties and reduce the susceptibility to the conventional Fermi liquid behavior of ordinary metals. These results imply that pairing mechanisms of superconductivity need to cope with competing spin density wave and charge density wave instabilities.