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https://hdl.handle.net/2142/25739
Description
Title
Thermal conductivity of superconducting niobium
Author(s)
Carlson, Jon Ross
Issue Date
1968
Doctoral Committee Chair(s)
Satterthwaite, C.B.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
thermal conductivity
superconducting niobium
magnetic field
single crystals
Language
en
Abstract
The magnetic field and temperature dependence of
the thermal conductivity of superconducting niobium have
been measured in magnetic fields which ranged .. from zero
to above the critical fields, and for temperatures which
ranged from 0.31 K to above the transition temperature.
Measurements were made on a single crystal cylindrical
specimen for which R300/R ~ 200. The thermal
4.2:N
conductivity in the superconducting state exhibited a
maximum near 1.80 K. This maximum has been attributed
to enhanced lattice conductivity as the electrons cono
dense into the ground state. Below 0.6 K the superconducting
state thermal conductivity showed an anomalous
3 departure from the expected T dependence for phonons.
The departure has been interpreted in terms of a two
energy gap model. Magnetic field measurements with the
field parallel to the heat flow showed a deep minimum
between H 1 and H at the temperature of the maximum
C C2
and at lower temperatures. The experimental results
near HC2 have been compared with Maki's prediction
that (dKII/dH)CX:(HC2-H)-1/2. Good qualitative agreement
was found) but the quantatative results gave a density
of states somewhat lower than the values obtained from
specific heat measurements.
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