Optical spectra of high-temperature superconductors

John Ruvalds

doi:10.1117/12.241758

10 June 1996 Optical spectra of high-temperature superconductors

John Ruvalds

Proceedings Volume 2696, Spectroscopic Studies of Superconductors; (1996) https://doi.org/10.1117/12.241758
Event: Photonics West '96, 1996, San Jose, CA, United States

Abstract

The concept of 'free' electrons which yields the Drude description of the conductivity works surprisingly well in conventional metals. By contrast, the infrared reflectivity of the cuprate superconductors deviates dramatically from Drude behavior and thus challenges theory to explain the origin of the anomalous electron damping and the related mass divergence which has implications for the existence of a Fermi surface. The controversial key issue of the carrier concentration in cuprates needs to be resolved by a conserving analysis of the puzzling conductivity. Raman spectra of cuprates also exhibit unconventional electronic contributions over a wide frequency range up to 1 eV, and recent data provide evidence for the symmetry of the superconducting energy gap. A microscopic theory for both the optical conductivity and the Raman anomalies in cuprates derives a linear frequency variation of the damping from electron-electron collisions on a 'nested' Fermi surface that refers to nearly parallel segments of an electron trajectory. Thus the nesting theory links the cuprate anomalies to phenomena in chromium and rare earth metals. Nesting also yields a novel mechanism for d-wave superconductivity that requires a Coulomb repulsion of intermediate strength and key nesting features that distinguish high T_c cuprates from other materials.

Citation Download Citation

John Ruvalds "Optical spectra of high-temperature superconductors", Proc. SPIE 2696, Spectroscopic Studies of Superconductors, (10 June 1996); https://doi.org/10.1117/12.241758

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