Experimental determination of the order parameter: response function of a superconductor

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:5379503

Goldman, A. M.

The order parameter response function of a superconductor can be obtained by incorporating it in an asymmetric tunneling junction with a higher T/sub c/ superconductor and measuring an excess current in the I-V characteristic. This current is then proportional to the imaginary part of the space and time Fourier transform of the response function with the frequency set by the bias voltage and the wave vector determined by a magnetic field applied parallel to the plane of the junction. Using this technique, studies of the dynamics of the superconducting order parameter have been undertaken above and below T/sub c/. Above T/sub c/ the time dependent Ginzburg-Landau equation accurately describes the dynamics. Below T/sub c/ a propagating mode is found which can be associated with fluctuations in the phase of the order parameter. Measurements of the magnetic impurity dependence of the response function have been used to study the ''anomalous'' term in the Gor'kov-Eliashberg theory which gives the coupling between order parameter fluctuations and fluctuations in the quasiparticle distribution function. Below T/sub c/ and in a current-carrying state, amplitude and phase fluctuations are coupled and the modes soften at the critical current.

• Research Organization: Minnesota Univ., Minneapolis (USA). School of Physics and Astronomy
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: EY-76-S-02-1569
• OSTI ID: 5379503
• Report Number(s): COO-1569-145; CONF-770872-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM
ALUMINIUM ALLOYS
CRITICAL CURRENT
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
ERBIUM ALLOYS
FILMS
FLUCTUATIONS
FUNCTIONS
LEAD
METALS
ORDER PARAMETERS
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
RESPONSE FUNCTIONS
SUPERCONDUCTING FILMS
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VARIATIONS