Microwave studies of high Tc copper oxide superconductors and NbN. In-house report

Technical Report · Fri Nov 01 04:00:00 EST 1991

OSTI ID:6581119

Chin, C C

This report covers several projects, namely: surface impedance measurements using both stripline and cavity resonators; microwave magnetic field dependence measurements of the surface impedance of NbN; determination of the upper critical field of YBa2Cu3O7 by microwave measurements; and the calculation of the angular dependence of an anisotropic superconductor. The temperature and frequency dependencies of the surface impedance of NbN thin films were measured using a stripline resonator from 4.2 to 13 K and from 0.5 to 10 GHz. At 4.2 K resonant cavity measurements of the surface resistance were made at 35 and 56 GHz. From the surface reactance measurements using both cavity and stripline techniques, we obtain the penetration depth extrapolated to T=0 K. Lamba(0)=3700A. For the stripline, the film thickness was approximately 8000 angstrom, which is about twice the measured penetration depth. The weak-coupling (full) Mattis-Bardeen theory appropriate for NbN was used to fit the temperature dependence on the surface resistance. Based on the quality of the weak-coupling fit to the data, we conclude that the strong-coupling effect is not important in the local and dirty limits. The correction of the stripline measurements of the surface resistance due to the finite film thickness is discussed.

• Research Organization: Rome Lab., Hanscom AFB, MA (United States)
• OSTI ID: 6581119
• Report Number(s): AD-A-260708/3/XAB; RL-TR--91-392
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
ANISOTROPY
BARIUM COMPOUNDS
BARIUM OXIDES
CAVITY RESONATORS
CHALCOGENIDES
COMPUTER CALCULATIONS
COPPER COMPOUNDS
CRITICAL FIELD
CUPRATES
DIAGNOSTIC USES
ELECTRONIC EQUIPMENT
EQUIPMENT
FILMS
FREQUENCY DEPENDENCE
HIGH-TC SUPERCONDUCTORS
IMPEDANCE
INTERMETALLIC COMPOUNDS
MAGNETIC FIELDS
MICROWAVE EQUIPMENT
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PENETRATION DEPTH
PNICTIDES
QUALITY ASSURANCE
REFRACTORY METAL COMPOUNDS
RESEARCH PROGRAMS
RESONATORS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
USES
YTTRIUM COMPOUNDS
YTTRIUM OXIDES