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TT: Fachverband Tiefe Temperaturen

TT 10: Poster Session: Superconductivity

TT 10.53: Poster

Montag, 14. März 2011, 14:00–18:00, P4

Raman light scattering on YBa₂Cu₃O₇/La_2/3Ca_1/3MnO₃ Superlattices — •Nadir Omar Driza, Mohammed Bakr, Santiago Blanco Canosa, Soltan Soltan, Hanns-Ulrich Habermeier, Giniyat Khaliullin, Mathieu Le Tacon, and Bernhard Keimer — Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany

Artificial superlattice (SL) structures offer a possibility of combining antagonistic order parameters such as superconductivity (SC) and ferromagnetism (FM). It was recently observed [1] that the interface between YBa₂Cu₃O₇ (YBCO) and La_2/3Ca_1/3MnO₃ (LCMO) exhibits an unusual orbital reconstruction different than that of either YBCO or LCMO. Therefore, it is of fundamental interest to explore proximity and inverse-proximity effects that take place at the vicinity of the interface between the two systems using Raman scattering (RS). We have performed RS experiments on YBCO/LCMO SLs with different thicknesses of YBCO, i.e., 5-50 nm and constant thickness of LCMO (10 nm). We focus our study on the 230 cm⁻¹ phonon, which arises from in-phase rotations of the MnO₆ octahedra and the 340 cm⁻¹ mode originating from out-of-phase vibrations of the oxygen atoms in the CuO₂ planes of YBCO. Our T-dependence measurements revealed a strong anomaly in the phonon frequency and linewidth of these modes at the SC- and Curie transition temperatures. The anomaly we observe appears to be tied to a competition between electronic instabilities at the YBCO/LCMO interfaces and the bulk electronic properties of both layers.
J. Chakhalian et al., Nature Phy. 2, 244 (2006).