J. Kiltz | Searcharxiv

arXiv2001

Superconductivity-induced changes of the phonon resonances in RBa_2Cu_3O_7 (R=rare earth)

We observe a characteristic energy $\hbarω_{c}\approx 2.1$ eV which separates regions of different behavior of the phonon intensities in the Raman spectra of the $R\rm Ba_2Cu_3O_7$ system. A superconductivity-induced drop of phonon intensities is found for the oxygen modes O(4) and O(2)-O(3) only for excitation energies below $\hbarω_c$. This intensity drop indicates an order parameter which affects energies in the vicinity of $\hbarω_c$.

cond-mat.supr-con↗

arXiv1999

Resonant Raman Study of Superconducting Gap and Electron-Phonon Coupling in YbBa2Cu3O7-delta

We investigate the electronic background as well as the O2-O3 mode at 330 cm^-1 of highly doped YbBa2Cu3O7-delta in B1g symmetry. Above the critical temperature Tc the spectra consist of an almost constant electronic background and superimposed phononic excitations. Below Tc the superconducting gap opens and the electronic background redistributes exhibiting a 2Delta peak at 320 cm^-1. We use a model that allows us to separate the background from the phonon. In this model the phonon intensity is assigned to the coupling of the phonon to inter- and intraband electronic excitations. For excitation energies between 1.96 eV and 2.71 eV the electronic background exhibits hardly any resonance. Accordingly, the intraband contribution to the phonon intensity is not affected. In contrast, the interband contribution vanishes below Tc at 1.96 eV while it remains almost unaffected at 2.71 eV.

cond-mat.supr-con↗