Search

Proposes a wide-band traveling wave amplifier using vortex flow transistors (VFT), a Josephson junction used as a current controlled voltage source. Description of a VFT; Means to be used in order to overcome the problem of low impedance and low power levels; Maximum average power possible in the load.

Describes the measurements of transresistance of the vortex flow transistor (VFT). Description of VFT; Maximum response frequency of the VFT; Experimental procedure; Results and discussion; Conclusions.

We present a detailed characterization of the dynamic properties of proximity-coupled Josephson junctions in YBa[sub 2]Cu[sub 3]O[sub 7] fabricated by electron-beam scribing. A full description of the low-temperature behavior includes nonequilibrium processes in the normal barrier as well as wide-junction effects resulting from the planar geometry. Above ∼40 K these junctions obey the standard (equilibrium) resistively-shunted junction (RSJ) model in applied magnetic field. At lower temperatures, the volt–ampere V(I) curves develop a temperature-dependent “excess critical current,” saturating at 0.5–0.75 of the total critical current. Below ∼10 K hysteresis is observed. The observed temperature dependence and magnitude of the excess current and hysteresis are qualitatively consistent with published calculations based on the time-dependent Ginzburg–Landau equations. At low temperatures, the V(I) curves in applied field deviate significantly from the RSJ model, which we attribute to wide-junction behavior with a nonuniform bias-current distribution. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A superconducting linear phase modulator using a single film device made of Tl-Ca-Ba-Cu-O for operation at 77 K is presented The modulator has been analyzed from 300 MHz to about 6 GHz with good linearity for peak phase deviations up to 100 rad. Modulation has been observed for carriers up to 35 GHz. [ABSTRACT FROM AUTHOR]

Presents a study which investigated three-terminal single-layer thin-film superconducting devices made of yttrium barium copper oxide and niobium. Information on the structure and direct current behavior of the device; Details of the test setup and radio frequency data; Conclusions.

Discusses the development of a thermally controlled, thin-film superconducting switch for the purpose of multiplexing superconducting quantum interference device (SQUID) detection coils. Layout of the superconducting switch; SQUID output that results from switching a single gradiometer.

Extended voltage–current (V–I) characteristics of [001] tilt YBa2Cu3O7-x bicrystal films having misorientation angles, θ, of 3° to 20° showed a substantial and progressive change with θ, when measured in large fields. Transmission electron microscopy of the 10° bicrystal showed the grain boundary to contain edge dislocations separated by channels of relatively undisturbed lattice. A large drop in the intergrain irreversibility field, H*, occurred between 10° and 15°, and the characteristics became qualitatively different by 20°. Both the microscopy and the electromagnetic data support a heterogeneous description of the grain boundary, consisting of strongly coupled channels that close at a misorientation angle of around 15°. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]