3 research outputs found
Suppression of Spontaneous Supercurrents in a Chiral p-Wave Superconductor
The superconducting state of SRO is widely believed to have chiral p-wave
order that breaks time reversal symmetry. Such a state is expected to have a
spontaneous magnetization, both at sample edges and at domain walls between
regions of different chirality. Indeed, muon spin resonance experiments are
interpreted as evidence of spontaneous magnetization due to domain walls or
defects in the bulk. However, recent magnetic microscopy experiments place
upper limits on the magentic fields at the sample edge and surface which are as
much as two orders of magnitude smaller than the fields predicted theoretically
for a somewhat idealized chiral p-wave superconductor. We investigate the
effects on the spontaneous supercurrents and magnetization of rough and pair
breaking surfaces for a range of parameters within a Ginzburg-Landau formalism.
The effects of competing orders nucleated at the surface are also considered.
We find the conditions under which the edge currents are significantly reduced
while leaving the bulk domain wall currents intact, are quite limited. The
implications for interpreting the existing body of experimental results on
superconducting SRO within a chiral p-wave model are discussed.Comment: Changes to section 3, typos remove
Is Sr2RuO4 a Chiral P-Wave Superconductor?
Much excitement surrounds the possibility that strontium ruthenate exhibits
chiral p-wave superconducting order. Such order would be a solid state analogue
of the A phase of He-3, with the potential for exotic physics relevant to
quantum computing. We take a critical look at the evidence for such
time-reversal symmetry breaking order. The possible superconducting order
parameter symmetries and the evidence for and against chiral p-wave order are
reviewed, with an emphasis on the most recent theoretical predictions and
experimental observations. In particular, attempts to reconcile experimental
observations and theoretical predictions for the spontaneous supercurrents
expected at sample edges and domain walls of a chiral p-wave superconductor and
for the polar Kerr effect, a key signature of broken time-reversal symmetry,
are discussed.Comment: To appear in the proceedings of LT25 (Amsterdam, August 2008
Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors
The search for broken time reversal symmetry (TRSB) in unconventional
superconductors intensified in the past year as more systems have been
predicted to possess such a state. Following our pioneering study of TRSB
states in SrRuO using magneto-optic probes, we embarked on a systematic
study of several other of these candidate systems. The primary instrument for
our studies is the Sagnac magneto-optic interferometer, which we recently
developed. This instrument can measure magneto-optic Faraday or Kerr effects
with an unprecedented sensitivity of 10 nanoradians at temperatures as low as
100 mK. In this paper we review our recent studies of TRSB in several systems,
emphasizing the study of the pseudogap state of high temperature
superconductors and the inverse proximity effect in superconductor/ferromagnet
proximity structures.Comment: A review pape