Hon. B.Sc. - University of Western Ontario - 1991
M.Sc. - University of British Columbia - 1994
(herewith)
Department of Physics and Astronomy
A strong linear temperature dependence for
was
found to exist below 50K for applied magnetic fields of 0.5T and
1.5T. This linear temperature dependence contradicts the consensus
of previous
SR studies which suggested a behaviour consistent
with conventional s-wave pairing of carriers in the superconducting
state. The presence of a linear term in the data reported here, supports
recent microwave cavity measurements in zero field and indicates the
existence of a more unconventional pairing state. In addition, a possible
field dependence for
at low temperatures was indicated
by the data, with
having
a range of
1347 - 1451Å and
1437 - 1496Å for the 0.5T and 1.5T data,
respectively. The range of these values was determined by fitting the data
several different ways. For each type of analysis,
was
found to be
greater and the linear term was stronger in the 0.5T data.
Furthermore, the 1.5T data appear to agree better with the microwave
cavity measurements.
Included in this thesis is a qualitative description of the conventional
s-wave pairing state and a proposed d-wave pairing state,
called
dx2-y2. The findings in this SR study
support the latter, but does not rule out the possibility of other
anisotropic pairing states or isotropic pairing theories in which
critical fluctuations persist down to very low temperatures.