Nuclear spin relaxation and quasiparticle excitations in superconducting aluminum--3d alloys

Journal Article · Tue Apr 01 04:00:00 EST 1980 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00118063· OSTI ID:5221718

Parvin, K; MacLaughlin, D E

Aluminum-27 nuclear spin--lattice relaxation times T/sub 1/ have been measured in the normal and superconducting states of dilute alloys of Mn, Cr, and V in aluminum. These measurements prove the spectrum of thermally excited quasiparticle states in the superconductor and its modification by nonmagnetic resonant impurities. Theoretical studies of such systems indicate that in the Hartree--Fock (HF) approximation the BCS character of the host is basically retained in the alloy, with a reduced pairing interaction and a small additional broadening of quasiparticle states at the gap edge. Spin-fluctuation improvements on the HF approximation renormalize the parameters involved, but do not change the basic picture. Our T/sub 1/ data indicate gap edge broadening an order of magnitude greater than predicted. The discrepancy is nearly as large for V and Cr impurities as for Mn, which makes it unlikely that localized spin fluctuations play an important role in the broadening. Recent speculation on the effect of dislocation pinning by resonant impurities may be relevant to these results.

• Research Organization: Department of Physics, University of California, Riverside, California
• OSTI ID: 5221718
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 39:1; ISSN JLTPA
• 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 27
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
ALUMINIUM ISOTOPES
BCS THEORY
CHROMIUM ALLOYS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HARTREE-FOCK METHOD
INTERACTIONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MANGANESE ALLOYS
MEISSNER-OCHSENFELD EFFECT
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
PAIRING INTERACTIONS
PHYSICAL PROPERTIES
QUASI PARTICLES
RELAXATION TIME
RESONANCE
STABLE ISOTOPES
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VANADIUM ALLOYS