High Tc superconductors

Karl F. Renk

doi:10.1117/12.2297755

1 October 1991 High T_c superconductors

Karl F. Renk

Proceedings Volume 1576, 16th International Conference on Infrared and Millimeter Waves; 157616 (1991) https://doi.org/10.1117/12.2297755
Event: 16th International Conference on Infrared and Millimeter Waves, 1991, Lausanne, Switzerland

Abstract

After four years of world wide research on high T_c, superconductors of the cuprate type a variety of different material families is known, with T_c values up to 125 K. Progress in material preparation and in the development of experimental and theoretical methods has lead to a basic understanding of various material properties, however, the nature of the pairing mechanism is yet unknown. In this paper some basic properties will be discussed. A second point will be concentrated on important optical properties from microwave to u.v. frequencies. Condensation of charge carriers can be accompanied with anomalous phonon behavior; at T_c anomalous changes of oscillator strengths of infrared active phonons and anomalous shifts of resonance frequencies of some phonons are observed. Condensation of charge carriers leads, furthermore, to a behavior of the (anisotropic) optical properties that may be described by superconducting energy gaps. For excitations along the copper oxide planes the optical properties can be described as arising from a superconducting energy gap 2∆(0)/kT_c≈7 . However, there remains at low temperatures intra-gap absorption that extends from microwave to far-infrared frequencies. In a third part of the paper, microwave and far-infrared applications of high T_c superconductors will be discussed, namely microwave antennas, Fabry-Perot filters and

Citation Download Citation

Karl F. Renk "High T_c superconductors", Proc. SPIE 1576, 16th International Conference on Infrared and Millimeter Waves, 157616 (1 October 1991); https://doi.org/10.1117/12.2297755

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