https://doi.org/10.1140/epjb/e2008-00343-2
Topological objects in two-gap superconductor
1
Center for Theoretical Physics and School of Physics,
College of Natural Sciences, Seoul National University,
Seoul 151-742, Korea
2
Institute of Modern Physics, Chinese Academy of Sciences, P.O. Box 31, Lanzhou 730000, P. R. China
Corresponding author: a ymcho@yongmin.snu.ac.kr
Received:
13
November
2007
Revised:
13
June
2008
Published online:
10
September
2008
We discuss the non-Abelian topological objects,
in particular the non-Abrikosov
vortex and the magnetic knot made of the
twisted non-Abrikosov vortex, in two-gap superconductor.
We show that there are two types of non-Abrikosov vortex in
Ginzburg-Landau theory of two-gap superconductor, the D-type which has
no concentration of the condensate at the core
and the N-type which has a non-trivial
profile of the condensate at the core, under a wide
class of realistic interaction potential.
We prove that these non-Abrikosov vortices can have
either integral or fractional magnetic flux, depending on
the interaction potential. We show that they are described by
the non-Abelian topology and
,
in addition to the well-known Abelian topology
.
Furthermore, we discuss the possibility to construct
a stable magnetic knot in two-gap superconductor by
twisting the non-Abrikosov vortex and connecting two periodic ends
together, whose knot topology
is described by the Chern-Simon
index of the electromagnetic potential.
We argue that similar topological objects may exist
in multi-gap or multi-layer superconductors and
multi-component Bose-Einstein condensates
and superfluids, and discuss how these topological objects
can be constructed in MgB2, Sr2RuO4, 3He, and liquid metallic hydrogen.
PACS: 74.20.-z – Theories and models of superconducting state / 74.20.De – Phenomenological theories (two-fluid, Ginzburg-Landau, etc.) / 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.) / 74.90.+n – Other topics in superconductivity
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008