RESUMEN
Two-dimensional electron gases (2DEGs) formed at oxide interfaces show a large variety of functional properties of major physical interest. Here, the peculiar electric transport behavior of the 2DEG formed at the LGO/STO oxide interface is studied under the application of light pulses of different amplitude, duration, and repetition rate, and by varying the sample temperature from 8 to 300 K. The experimental results evidence a persistent photoconductivity, intimately related to the complex physics of this system. These findings suggest the possibility of using the oxide interfaces for advanced applications as, for example, energy conversion or information storage.
RESUMEN
Two kinds of epitaxial structures were grown by standard pulsed laser deposition on (001) Si, namely La(0.7)Sr(0.3)MnO(3)/Bi(4)Ti(3)O(12)/CeO(2) /YSZ/Si (BTO-based), and La(0.7)Sr(0.3)MnO(3)/SrTiO(3)/CeO(2) /YSZ/Si (STO-based) multilayers. The samples were investigated by means of x-ray diffraction, transmission electron microscopy, magnetic and transport measurements. The Curie temperature T(C) of the BTO-based samples was found to be higher (360 K) than for the typical reference epitaxial LSMO film grown on (001) SrTiO(3) single crystal (345 K), due to high compressive in-plane strain. The STO-based samples show high structural quality, low roughness and high T(C) (350 K), making them interesting candidates for use in innovative LSMO-based bolometers or spintronic devices operating at room temperature.
RESUMEN
We report preliminary results on the optical driving and spectroscopic detection of Raman-active features in thin films of the high-temperature superconductor YBa(2)Cu(3)O(7) in its normal phase by means of coherent Stokes and anti-Stokes Raman scattering, in a reflection geometry. Reference measurements on germanium are also reported. We observe phonon resonances which interfere coherently with a broad electronic resonance centered at zero frequency, giving rise to characteristic asymmetric spectral features. Our measurements provide a first step towards applying nonlinear optical wave-mixing spectroscopy to correlated electron systems.