The anisotropy of the upper critical field of chevrel phase compounds
Pazol, Brian George
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https://hdl.handle.net/2142/28672
Description
Title
The anisotropy of the upper critical field of chevrel phase compounds
Author(s)
Pazol, Brian George
Issue Date
1988
Doctoral Committee Chair(s)
Ginsberg, D.M.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
anisotropy
upper critical field
chevrel phase compounds
Language
en
Abstract
The anisotropy of the upper critical field has been measured on deoxygenated single crystals of the Chevrel phases PbMo6Ss and Cu1.sMo6Ss. Data were taken with the applied field pointing in various directions in the hexagonal (2IO) and (001) planes. At each of a series of field values the superconducting transition temperature oscillated as a function of direction. Since the Hc2 versus T curve is linear in the field region we probed, the shape of the anisotropy in T c at constant H is the same as the anisotropy of the upper critical field, Hc2. at constant T. The data reflect the low temperature symmetry of the crystal structure. The PbMo6S8 data display two-fold symmetry in the (2TO) plane and no measurable anisotropy in the (001) plane. The data were fit to the effective mass model
with uniaxial symmetry. A two-fold symmetry was observed in the Cu1.sMo6S8 in the (2TO) plane. Oscillations with three-fold symmetry have been observed for the first time in the (001) plane. The effective mass model was unable to explain the observed behavior, so the data were fit with an expansion of spherical harmonics with triclinic symmetry.
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