8 research outputs found
Supercurrents through gated superconductor-normal-metal-superconductor contacts: the Josephson-transistor
We analyze the transport through a narrow ballistic superconductor-normal-
metal-superconductor Josephson contact with non-ideal transmission at the
superconductor-normal-metal interfaces, e.g., due to insulating layers,
effective mass steps, or band misfits (SIN interfaces). The electronic spectrum
in the normal wire is determined through the combination of Andreev- and normal
reflection at the SIN interfaces. Strong normal scattering at the SIN
interfaces introduces electron- and hole-like resonances in the normal region
which show up in the quasi-particle spectrum. These resonances have strong
implications for the critical supercurrent which we find to be determined
by the lowest quasi-particle level: tuning the potential to the
points where electron- and hole-like resonances cross, we find sharp peaks in
, resulting in a transitor effect. We compare the performance of
this Resonant Josephson-Transistor (RJT) with that of a Superconducting Single
Electron Transistor (SSET).Comment: to appear in PRB, 11 pages, 9 figure
Magnetoresistance of one-dimensional subbands in tunnel-coupled double quantum wires
We study the low-temperature in-plane magnetoresistance of tunnel-coupled quasi-one-dimensional quantum wires. The wires are defined by two pairs of mutually aligned split gates on opposite sides of a < 1 micron thick AlGaAs/GaAs double quantum well heterostructure, allowing independent control of their widths. In the ballistic regime, when both wires are defined and the field is perpendicular to the current, a large resistance peak at ~6 Tesla is observed with a strong gate voltage dependence. The data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands