Dahm, T.V.; Hinkov, V.; Borisenko, S.V.; Kordyuk, A.A.; Zabolotnyy, V.B.; Fink, J.; Büchner, B.; Scalapino, D.J.; Hanke, W.; Keimer, B.: Strength of the spin-fluctuation-mediated pairing interaction in a high-temperature superconductor. Nature Physics 5 (2009), p. 217-221
10.1038/NPHYS1180
Abstract:
Theories based on the coupling between spin fluctuations and fermionic quasiparticles are among the leading contenders to explain the origin of high-temperature superconductivity, but estimates of the strength of this interaction differ widely1. Here, we analyse the charge- and spin-excitation spectra determined by angle-resolved photoemission and inelastic neutron scattering, respectively, on the same crystals of the high-temperature superconductor YBa2Cu3O6:6. We show that a self-consistent description of both spectra can be obtained by adjusting a single parameter, the spin–fermion coupling constant. In particular, we find a quantitative link between two spectral features that have been established as universal for the cuprates, namely high-energy spin excitations2–7 and ‘kinks’ in the fermionic band dispersions along the nodal direction8–12. The superconducting transition temperature computed with this coupling constant exceeds 150 K, demonstrating that spin fluctuations have sufficient strength to mediate high-temperature superconductivity.