ELECTRODYNAMICS OF HIGH-TEMPERATURE SUPERCONDUCTORS INVESTIGATED WITHCOHERENT TERAHERTZ PULSE SPECTROSCOPY

Recent experimental investigations of the electrodynamic properties of high-temperature superconductors in the terahertz regime are reviewed . Transmission measurements were performed with use of coherent terahe rtz pulse spectroscopy, which enables us to extract directly the frequ ency-dependent complex conductivity sigma(1) + i sigma(2). Investigati ons of both pure YBa2Cu3O7-delta and the related alloy Y1-xPrxBa2Cu3O7 -delta were conducted over a temperature range from 300 K down to 10 K . From these measurements we can extract the temperature-dependent Lon don penetration depth lambda L(T), the plasma frequency omega(p), and the quasi-particle scattering time tau(T). The implications of our mea surements for contemporary theories of high-T-c superconductivity are discussed. (C) 1996 Optical Society of America.