Interaction of phonons with intraband electronic excitations and crystal field transitions in Raman spectra of (Nd,Eu,Gd)Ba.sub.2./sub.Cu.sub.3./sub.O.sub.y./sub. crystals

0448241 - FZÚ 2016 RIV CH eng J - Journal Article
Rameš, Michal - Železný, Vladimír - Gregora, Ivan - Wolf, T. - Jirsa, Miloš
Interaction of phonons with intraband electronic excitations and crystal field transitions in Raman spectra of (Nd,Eu,Gd)Ba₂Cu₃O_y crystals.
Materials Science and Engineering B-Advanced Functional Solid-State Materials. Roč. 197, Jul (2015), 10-17. ISSN 0921-5107. E-ISSN 1873-4944
R&D Projects: GA MŠMT(CZ) ME10069
Institutional support: RVO:68378271
Keywords : cuprate superconductors * phonons * crystal field * vortex pinning
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 2.331, year: 2015

Intraband electronic excitations, phonons, and crystal field transitions of two unique (Nd,Eu,Gd)Ba2Cu3Oy single crystals with different Eu/Gd ratio were studied by Raman spectroscopy. The spectra were measured above and below critical temperature. The phonon symmetries were determined from the angular dependence of the spectra. The line shapes of barium, planar oxygen, and apical oxygen ions’ vibrations were affected by interaction of the phonons with intraband electronic excitations. We fitted the spectra at all measured temperatures and disentangled the phonon contributions from those of the intraband electronic excitations and identified corresponding interference terms. Below Tc, a broad, superconductivity-induced high-frequency peak appeared in the spectra of both crystals. Damping of the Raman active phonons in our crystals correlated well with varying pinning disorder in the crystals.
Permanent Link: http://hdl.handle.net/11104/0249987