Measurements of the point contact tunnelling spectra of the superconductors La,-,Sr,CuO,-, and EuBa,Cu,O, with Nb were performed. The superconducting gap A at 4.2 K with a ratio 2A/Tc of about 10 was obtained. The structure of the tunnelling spectra at voltages above the gap shows that pairing originates from the electron-electron interaction via phonons and possibly via some other excitations of electronic nature with energy about 100 meV.

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Cr:ZnSe thin films were grown by molecular-beam epitaxy with the long-term goal of demonstrating a route for the development of transitional-metal-doped semiconductor lasers. Photoluminescence (PL) and PL lifetime measurements of doped thin films and bulk crystals indicate that Cr is incorporated in the optically active Cr2+ state up to levels of 5×1019cm−3. The shape of PL spectra and lifetime measurements of doped thin films compares favorably with that reported for bulk samples. A microcavity formed by film interfaces is responsible for differences in spontaneous emission observed between films and bulk crystals.

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