Far-infrared absorption of thin superconducting aluminum films in the pair-breaking and paramagnetic limits

Journal Article · Fri Aug 01 04:00:00 EDT 1986 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.34.1582· OSTI ID:5588070

van Bentum, P J.M.; Wyder, P

Measurements are presented of the far-infrared absorption of thin superconducting aluminum films in a parallel magnetic field. The results for moderately thick films (d-italicroughly-equal10 nm) are in reasonable agreement with the Abrikosov-Gor'kov theory of pair breaking. The experimental results for ultrathin films (d-italic< or =5 nm) in the paramagnetic limit show that the spectroscopic gap ..cap omega../sub g-italic/ shifts linearly with the magnetic field H-italic, according to h-dash-bar..cap omega../sub g-italic/ = 2..delta..-2..mu../sub 0/..mu../sub B/H. This shift of the gap is attributed to a photon-absorption process, where the quasiparticle spin is flipped with respect to the static field. The complex conductivity of a paramagnetically limited film in a parallel magnetic field is calculated, both within the Bardeen-Cooper-Schrieffer framework and using the more general Green's-function formalism with the inclusion of spin-orbit and (magnetic) spin-flip scattering. For the ultrathin Al films we obtain a good quantitative agreement between theory and experiment, assuming a spin-orbit coupling h-dash-bar/tau/sub SO/..delta..roughly-equal0.1 and a reduced value of the imaginary part of the conductivity, probably due to strong electron-phonon coupling effects.

• Research Organization: Research Institute for Materials, University of Nijmegen, The Netherlands
• OSTI ID: 5588070
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 34:3; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals &amp; Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
&amp; Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABRIKOSOV THEORY
ABSORPTION SPECTRA
ALUMINIUM
CRITICAL FIELD
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELECTRON-PHONON COUPLING
ELEMENTS
ENERGY-LEVEL DENSITY
FAR INFRARED RADIATION
FILMS
INFRARED RADIATION
LIMITING VALUES
MAGNETIC FIELDS
MAGNETISM
METALS
PARAMAGNETISM
PHYSICAL PROPERTIES
RADIATIONS
SPECTRA
SUPERCONDUCTING FILMS
SUPERCONDUCTIVITY
ZEEMAN EFFECT