Properties of NbN granular bridges in a microwave SQUID

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5397204

Steiner, R L

A series of superconducting NbN granular bridges were studied by measuring their responses as microwave SQUIDs and determining their dynamic impedance at 9.58 GHz. The samples were placed in a microwave resonant cavity and measurements made of the complex reflection coefficient as a function of incident microwave power, applied magnetic flux, and temperature. The bridges were 1 ..mu..m long, 1-50 ..mu..m wide and 3-8 nm thick and contained in a thick NbN ring approximately 1 mm in diameter. From the measurements of SQUID response as a function of microwave power, the critical current versus temperature was found to fitted Ambegaokar-Baratoff theory, except one sample which fit a mean-field theory. The SQUID response itself was found to behave systematically with temperature. The impedance measurements were taken at low incident power and at temperature near T/sub c/, where the critical current is small enough to allow phase biasing of the bridge by the flux in the nonhysteretic regime. From measurements on two samples, the dynamic inductance as a function of phase was deduced.

• Research Organization: Virginia Univ., Charlottesville (USA)
• OSTI ID: 5397204
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRIC BRIDGES
ELECTRIC IMPEDANCE
ELECTRICAL EQUIPMENT
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
FUNCTIONS
IMPEDANCE
MEASURING INSTRUMENTS
MEASURING METHODS
MICROWAVE EQUIPMENT
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
REFRACTORY METAL COMPOUNDS
RESPONSE FUNCTIONS
SQUID DEVICES
SUPERCONDUCTING DEVICES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE