11 research outputs found
Observation of superluminal geometrical resonances in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions
We study Fiske steps in small Bi2Sr2CaCu2O8+x mesa structures, containing
only few stacked intrinsic Josephson junctions. Careful alignment of magnetic
field prevents penetration of Abrikosov vortices and facilitates observation of
a large variety of high quality geometrical resonances, including superluminal
with velocities larger than the slowest velocity of electromagnetic waves. A
small number of junctions limits the number of resonant modes and allows
accurate identification of modes and velocities. It is shown that superluminal
geometrical resonances can be excited by subluminal fluxon motion and that
flux-flow itself becomes superluminal at high magnetic fields. We argue that
observation of high-quality superluminal geometrical resonances is crucial for
realization of the coherent flux-flow oscillator in the THz frequency range
Disparity of superconducting and pseudogap scales in low-Tc Bi-2201 cuprates
We experimentally study transport and intrinsic tunneling characteristics of
a single-layer cuprate Bi(2+x)Sr(2-y)CuO(6+delta) with a low superconducting
critical temperature Tc < 4 K. It is observed that the superconducting energy,
critical field and fluctuation temperature range are scaling down with Tc,
while the corresponding pseudogap characteristics have the same order of
magnitude as for high-Tc cuprates with 20 to 30 times higher Tc. The observed
disparity of the superconducting and pseudogap scales clearly reveals their
different origins.Comment: 5 page
Low-loss terahertz superconducting plasmonics
In the plasmonic regime, an electromagnetic wave bounded to the surface of a conductor can be confined to a region much smaller than its wavelength in free space. A major problem of plasmonic technology, however, is associated with large losses that these surface modes exhibit, intimately linked to Ohmic resistance of metals. In this work, we show that due to their dominant kinetic inductance, superconductors are intriguing yet natural plasmonic media capable of supporting low-loss plasmon waves with extreme confinement and the potential to serve as information carriers in compact terahertz data processing circuits.<br/