518 research outputs found
Theory of Josephson Phenomena in Superfluid 3He
Quite detailed theoretical description of superfluid 3He is possible on
length scales that are much larger than the atomic scale. We discuss weak links
between two bulk states of 3He-B. The current through the weak link is
determined by the bound states at the link. The bound state energies are spin
split depending on the order parameters in the bulk. As a result, unusual
current-phase relations with pi state appear. For not too weak links, the order
parameter in the bulk is modified because of the Josephson coupling. This leads
to a stronger pi state and to an additional current at constant pressure bias.
The theoretical results are compared with experiments.Comment: 6 pages, 9 figures, talk on LT-24, Orlando, Florid
Elementary vortex pinning potential in superconductors with unconventional order parameter
The elementary vortex pinning potential is studied in unconventional
superconductors within the framework of the quasiclassical theory of
superconductivity. Numerical results are presented for d-, anisotropic s-, and
isotropic s-wave superconductors to show explicitly that in unconventional
superconductors the vortex pinning potential is determined mainly by the loss
of the condensation energy in bulk due to the presence of the pinning center,
i.e., by the breakdown of the Anderson's theorem. It is found that the vortex
pinning energy in the d-wave pairing case is 4 -- 13 times larger than those in
the s-wave pairing cases. This means that an enhancement of pinning effect in
unconventional superconductors occurs due to the breakdown of the Anderson's
theorem. The case of a chiral p-wave superconductor is also investigated in
terms of the vortex core states subject to the Andreev reflection, where
important is whether the vorticity and chirality are parallel or antiparallel.Comment: 7 pages, 4 figures included; paper for Proceedings of the symposium
SDP2001, Tokyo, 200
- …