Quantum Magnetic Excitations from Stripes in Cuprate Superconductors

Preprint
Publisher Website
Google Scholar
  • 30 January 2004
Abstract
The nature of the antiferromagnetic spin excitations in copper-oxide superconductors, generally believed to play a significant role in the pairing mechanism, remains a matter of controversy. One school of thought holds that they are associated with the response of low-energy charge carriers close to the Fermi energy. In an alternative approach, the spin fluctuations are due to remnants of the antiferromagnetic-insulator phase that is obtained when the charge carriers are removed; spatial segregation of the carriers into inhomogeneous patterns, such as stripes, allow the antiferromagnetic regions to survive. Recently, it has been argued that measurements of the dispersion of spin excitations in superconducting YBa(2)Cu(3)O(6+x) are incompatible with the latter picture. Here we present a neutron-scattering study of magnetic fluctuations in a particular cuprate, La(1.875)Ba(0.125)CuO(4), that exhibits inhomogeneous, charge-stripe order. We show that 1) the high-energy excitations are distinct from spin waves and similar to those of quantum spin structures, such as two-leg ladders, and 2) dispersion features similar to those in YBa(2)Cu(3)O(6+x) are present. This implies that the important magnetic correlations in the cuprates universally result from charge inhomogeneity.

This publication has 0 references indexed in Scilit: