Superconducting La2CuO4+x prepared by oxygenation at high pressure: a Raman-scattering study

Kevin F. McCarty; J. E. Schirber; S.-W. Cheong; Z. Fisk

doi:10.1117/12.22897

1 November 1990 Superconducting La2CuO4+x prepared by oxygenation at high pressure: a Raman-scattering study

Kevin F. McCarty, J. E. Schirber, S.-W. Cheong, Z. Fisk

Proceedings Volume 1336, Raman and Luminescence Spectroscopies in Technology II; (1990) https://doi.org/10.1117/12.22897
Event: 34th Annual International Technical Symposium on Optical and Optoelectronic Applied Science and Engineering, 1990, San Diego, CA, United States

Abstract

Superconducting crystals of La2CuO4+ prepared by high-pressure oxygenation have been analyzed by Ramán spectroscopy. A direct comparison of the role of excess oxygen was made by examining the same crystals with and without excess oxygen. La2CuO4+, like non-superconducting La2CuO4.O, is found to have a soft phonon that drives an orthorhombic to tetragonal phase transition. In both its tetragonal and orthorhombic forms, La2CuO4+ has a phonon peak at 630 cm1 that is absent in La2CuO4.O. The frequency of this peak is suggestive of a peroxide-like species in La2CuO4+. Surprisingly, the Ag phonons of La2CuO4.O and La2CuO4+ occur at essentially the same frequency. While La2CuO4.O has a well-defined peak from double-magnon scattering, no welldefined double-magnon scattering is observed in La2CuO4+, even in its phase-separated form.

Citation Download Citation

Kevin F. McCarty, J. E. Schirber, S.-W. Cheong, and Z. Fisk "Superconducting La2CuO4+x prepared by oxygenation at high pressure: a Raman-scattering study", Proc. SPIE 1336, Raman and Luminescence Spectroscopies in Technology II, (1 November 1990); https://doi.org/10.1117/12.22897

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