Magnetic-Field-Tunable Superconducting Rectifier
- Tuesday, 01 December 2009
This device would be useful in superconducting circuit applications.Superconducting electronic components have been developed that provide current rectification that is tunable by design and with an externally applied magnetic field to the circuit component. The superconducting material used in the device is relatively free of pinning sites with its critical current determined by a geometric energy barrier to vortex entry. The ability of the vortices to move freely inside the device means this innovation does not suffer from magnetic hysteresis effects changing the state of the superconductor. The invention requires a superconductor geometry with opposite edges along the direction of current flow. In order for the critical current asymmetry effect to occur, the device must have different vortex nucleation conditions at opposite edges. Alternative embodiments producing the necessary conditions include edges being held at different temperatures, at different local magnetic fields, with different current-injection geometries, and structural differences between opposite edges causing changes in the size of the geometric energy barrier. An edge fabricated with indentations of the order of the coherence length will significantly lower the geometric energy barrier to vortex entry, meaning vortex passage across the device at lower currents causing resistive dissipation.
The existing prototype is a two-terminal
device consisting of a thin-film superconducting strip operating at a temperature
below its superconducting
transition temperature (Tc). Opposite
ends of the strip are connected to electrical
leads made of a higher Tc superconductor.
The thin-film lithographic
process provides an easy means to alter
edge-structures, current-injection geo -
metries, and magnetic-field conditions
at the edges. The edge-field conditions
can be altered by using local field(s)
generated from dedicated higher Tc
leads or even using the device’s own
higher Tc superconducting leads.
This work was done by John E. Sadleir of Goddard Space Flight Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Semiconductors & ICs category. GSC-15643-1
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