31 research outputs found
Effect of Spin-Orbit Interaction in Spin-Triplet Superconductor: Structure of -vector and Anomalous O-NQR Relaxation in SrRuO
Supposing the spin-triplet superconducting state of SrRuO, the
spin-orbit (SO) coupling associated with relative motion in Cooper pairs is
calculated by extending the method for the dipole-dipole coupling given by
Leggett in the superfluid He. It is shown that the SO coupling works only
in the equal-spin pairing (ESP) state to make the pair angular momentum
and the pair spin angular momentum parallel with each other. The SO coupling gives rise to the internal
Josephson effect in a chiral ESP state as in superfluid A-phase of He with
a help of an additional anisotropy arising from SO coupling of atomic origin
which works to direct the {\bf d}-vector into -plane. This resolves the
problem of the anomalous relaxation of O-NQR and the structure of {\bf
d}-vector in SrRuO.Comment: Accepted for publication in J. Phys. Soc. Jpn. vol.79 (2010), No.2
(February issue); 18 pages, 2 figure
Evaluation of Spin-Triplet Superconductivity in Sr2RuO4
This review presents a summary and evaluations of the superconducting
properties of the layered ruthenate Sr2RuO4 as they are known in the autumn of
2011. This paper appends the main progress that has been made since the
preceding review by Mackenzie and Maeno was published in 2003. Here, special
focus is placed on the critical evaluation of the spin-triplet, odd-parity
pairing scenario applied to Sr2RuO4. After an introduction to superconductors
with possible odd-parity pairing, accumulated evidence for the pairing symmetry
of Sr2RuO4 is examined. Then, significant recent progress on the theoretical
approaches to the superconducting pairing by Coulomb repulsion is reviewed. A
section is devoted to some experimental properties of Sr2RuO4 that seem to defy
simple explanations in terms of currently available spin-triplet scenario. The
next section deals with some new developments using eutectic boundaries and
micro-crystals, which reveals novel superconducting phenomena related to chiral
edge states, odd-frequency pairing states, and half-fluxoid states. Some of
these properties are intimately connected with the properties as a topological
superconductor. The article concludes with a summary of knowledge emerged from
the study of Sr2RuO4 that are now more widely applied to understand the physics
of other unconventional superconductors, as well as with a brief discussion of
relatively unexplored but promising areas of ongoing and future studies of
Sr2RuO4.Comment: 31 pages, 35 figures, published in J. Phys. Soc. Jpn. as a review
article of Special Topic