21 research outputs found
Nonlinear electrodynamics of p-wave superconductors
We consider the Maxwell-London electrodynamics of three dimensional
superconductors in p-wave pairing states with nodal points or lines in the
energy gap. The current-velocity relation is then nonlinear in the applied
field, cubic for point nodes and quadratic for lines. We obtain explicit
angular and depth dependent expressions for measurable quantities such as the
transverse magnetic moment, and associated torque. These dependences are
different for point and line nodes and can be used to distinguish between
different order parameters. We discuss the experimental feasibility of this
method, and bring forth its advantages, as well as limitations that might be
present.Comment: Fourteen pages RevTex plus four postscript figure
Muon Spin Rotation study of the system
We report a study of the organic compound in both a sample
cooled very slowly through the anion ordering temperature (relaxed state) and a
sample cooled more rapidly (intermediate state). For the relaxed state the
entire sample is observed to be superconducting below about T_c ~ 1.2 K. The
second moment of the internal field distribution was measured for the relaxed
state yielding an in-plane penetration depth of ~ 12000 Angstroms. The
intermediate state sample entered a mixed phase state, characterized by
coexisting macroscopic sized regions of superconducting and spin density wave
(SDW) regions, below T_c ~ 0.87 K. These data were analyzed using a
back-to-back cutoff exponential function, allowing the extraction of the first
three moments of the magnetic field distribution. Formation of a vortex lattice
is observed below 0.87 K as evidenced by the diamagnetic shift for the two
fields in which we took intermediate state data.Comment: 6 pages, 3 figures, to be submitted to Physica
Antiferromagnetic Domains and Superconductivity in UPt3
We explore the response of an unconventional superconductor to spatially
inhomogeneous antiferromagnetism (SIAFM). Symmetry allows the superconducting
order parameter in the E-representation models for UPt3 to couple directly to
the AFM order parameter. The Ginzburg-Landau equations for coupled
superconductivity and SIAFM are solved numerically for two possible SIAFM
configurations: (I) abutting antiferromagnetic domains of uniform size, and
(II) quenched random disorder of `nanodomains' in a uniform AFM background. We
discuss the contributions to the free energy, specific heat, and order
parameter for these models. Neither model provides a satisfactory account of
experiment, but results from the two models differ significantly. Our results
demonstrate that the response of an E_{2u} superconductor to SIAFM is strongly
dependent on the spatial dependence of AFM order; no conclusion can be drawn
regarding the compatibility of E_{2u} superconductivity with UPt3 that is
independent of assumptions on the spatial dependence of AFMComment: 12 pages, 13 figures, to appear in Phys. Rev.