Article

Unconventional rf photoresponse from a superconducting spiral resonator

(Impact Factor: 3.66). 03/2012; 85(13). DOI: 10.1103/PhysRevB.85.134535
Source: arXiv

ABSTRACT Superconducting thin film resonators employing strip geometries show great
promise in rf/microwave applications due to their low loss and compact nature.
However, their functionality is limited by nonlinear effects at elevated
rf/microwave powers. Here, we show that by using a planar spiral geometry
carrying parallel currents in adjacent turns, this limitation can be minimized.
We investigate the rf current distributions in spiral resonators implemented
with Nb thin films via laser scanning microscopy. The rf current density
profile along the width of the individual turns of the resonators reveals an
unconventional trend: maximum current in the middle of the structure and
decaying toward its edges. This unusual behavior is associated with the
circular nature of the geometry and the cancellation of magnetic field between
the turns, which is favorable for handling high powers since it allows the
linear characteristics to persist at high rf current densities.

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Available from: Alexander P. Zhuravel, Jan 15, 2014
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• "At high temperatures and RF powers the resonance characteristics drastically change in a nonlinear fashion. This can be very useful for switching the superconducting meta-atoms into a high-loss state [12], [13]. At temperatures too close to T c the resonator looses many of its useful features, such as a high quality factor, and probably is less attractive for device applications. "
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