Magnetic Resonant Mode in the Single-Layer High Temperature Superconductor Tl$_2$Ba$_2$Cu$_{6+\delta}$

摘要

An unusual spin excitation mode observed by neutron scattering has inspirednumerous theoretical studies of the interplay between charged quasiparticlesand collective spin excitations in the copper oxide high temperaturesuperconductors. The mode has thus far only been observed in materials withcrystal structures consisting of copper oxide bilayers, and it is notablyabsent in the single-layer compound La$_{2-x}$Sr$_{x}$CuO$_{4+\delta}$. Neutronscattering data now show that the mode is present inTl$_2$Ba$_2$Cu$_{6+\delta}$, a single-layer compound with T$_c$ $\sim$ 90 K,thus demonstrating that it is a generic feature of the copper oxidesuperconductors, independent of the layer sequence. This restricts thetheoretical models for the origin of the resonant mode and its role in themechanism of high temperature superconductivity.