Josephson plasma resonance observed in Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ superconducting thin films using terahertz time-domain spectroscopy

Abstract

Summary form only given. The c-axis Josephson plasma resonance (JPR) in highly anisotropic layered cuprate superconductors originates from the interlayer tunneling of Cooper pairs. The JPR, /spl omega//sub pc/=c//spl lambda//sub c//spl radic/(/spl epsi//sub /spl infin///sup c/) is directly related to the London penetration depth along the c-axis, /spl lambda//sub c/, and is thus a fundamental probe of the superconducting state and an excellent tool to study these highly anisotropic systems. /spl epsi//sub /spl infin///sup c/ is the high frequency dielectric constant along the c-axis. For T/spl Lt/T/sub c/, the temperature dependence of /spl lambda//sub c/ is related to the symmetry of the order parameter. For T close to T. the appearance of the JPR probes the onset of interlayer phase coherence. Furthermore, the JPR spectral width is a measure of the quasiparticle scattering rate. In a magnetic field, the JPR probes the correlation of pancake vortices along the c-axis and is a tool to study the B-T phase diagram. The JPR of high-T/sub c/ superconductors with extreme anisotropy such as the bismuth, thallium, and mercury based high-T/sub c/ superconductors lies in the far-infrared and is thus amenable to study using terahertz time-domain spectroscopy (THz-TDS). We have measured the JPR in Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ superconducting thin films employing THz-TDS in transmission.