scispace - formally typeset
Search or ask a question
Topic

Fractional vortices

About: Fractional vortices is a research topic. Over the lifetime, 100 publications have been published within this topic receiving 5027 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, a review of recent developments in the phenomenological description of unconventional superconductivity is presented, starting with the BCS theory of superconductivities with anisotropic Cooper pairing, and the group-theoretical derivation of the generalized Ginzburg-Landau theory for unconventional supercondivity.
Abstract: This article is a review of recent developments in the phenomenological description of unconventional superconductivity. Starting with the BCS theory of superconductivity with anisotropic Cooper pairing, the authors explain the group-theoretical derivation of the generalized Ginzburg-Landau theory for unconventional superconductivity. This is used to classify the possible superconducting states in a system with given crystal symmetry, including strong-coupling effects and spin-orbit interaction. On the basis of the BCS theory the unusual low-temperature properties and the (resonant) impurity scattering effects are discussed for superconductors with anisotropic pairing. Using the Ginzburg-Landau theory, the authors study several bulk properties of such superconductors: spontaneous lattice distortion, upper critical magnetic field, splitting of a phase transition due to uniaxial stress. Two possible mechanisms for ultrasound absorption are discussed: collective modes and damping by domain-wall motion. The boundary conditions for the Ginzburg-Landau theory are derived from a correlation function formulation and by group-theoretical methods. They are applied to a study of the Josephson and proximity effects if unconventional superconductors are involved there. The magnetic properties of superconductors that break time-reversal symmetry are analyzed. Examples of current and magnetic-field distributions close to inhomogeneities of the superconducting order parameter are given and their physical origin is discussed. Vortices in a superconductor with a multicomponent order parameter can exhibit various topological structures. As examples the authors show fractional vortices on domain walls and nonaxial vortices in the bulk. Furthermore, the problem of the possible coexistence of a superconducting and a magnetically ordered phase in an unconventional superconductor is analyzed. The combination of two order parameters that are almost degenerate in their critical temperature is considered with respect to the phase-transition behavior and effects on the lower and upper critical fields. Because heavy-fermion superconductors---which are possible realizations of unconventional superconductivity---have been the main motivation for the phenomenological studies presented here, the authors compare the theoretical results with the experimental facts and data. In particular, they emphasize the intriguing features of the compound U${\mathrm{Pt}}_{3}$ and consider in detail the alloy ${\mathrm{U}}_{1\ensuremath{-}x}{\mathrm{Th}}_{x}{\mathrm{Be}}_{13}$.

1,577 citations

Journal ArticleDOI
Tin-Lun Ho1
TL;DR: In this article, the ground states of spin-1 bosons can be either ferromagnetic or polar, depending on the scattering lengths in different angular momentum channels, and the collective modes of these states have very different spin character and spatial distributions.
Abstract: We show that in an optical trap the ground states of spin-1 bosons such as ${}^{23}\mathrm{Na}$, ${}^{39}\mathrm{K}$, and ${}^{87}\mathrm{Rb}$ can be either ferromagnetic or ``polar" states, depending on the scattering lengths in different angular momentum channels. The collective modes of these states have very different spin character and spatial distributions. While ordinary vortices are stable in the polar state, only those with unit circulation are stable in the ferromagnetic state. The ferromagnetic state also has coreless (or Skyrmion) vortices like those of ${}^{3}\mathrm{He}\ensuremath{-}A$.

1,076 citations

Journal ArticleDOI
TL;DR: In this article, the Bogoliubov theory is extended to a Bose-Einstein condensation with internal degrees of freedom, realized recently in 23 Na gases where several hyperfine states are simultaneously cooled optically.
Abstract: The Bogoliubov theory is extended to a Bose-Einstein condensation with internal degrees of freedom, realized recently in 23 Na gases where several hyperfine states are simultaneously cooled optically. Starting with a Hamiltonian constructed from general gauge and spin rotation symmetry principles, fundamental equations for condensate are derived. The ground state where time reversal symmetry is broken in some cases and low-lying collective modes, e.g. spin and density wave modes, are discussed. Novel vortex as a topological defect can be created experimentally.

711 citations

Journal ArticleDOI
TL;DR: It is shown that, in two-gap superconductors and equivalent extended Faddeev model, there exist vortices which carry an arbitrary fraction of magnetic flux quantum.
Abstract: We discuss linear topological defects allowed in two-gap superconductors and equivalent extended Faddeev model. We show that, in these systems, there exist vortices which carry an arbitrary fractio ...

259 citations

Journal ArticleDOI
TL;DR: In this paper, a simple explanation of complex magnetic patterns observed in ferromagnetic nanostructures is provided. But the authors do not identify elementary topological defects in the field of magnetization, such as ordinary vortices in the bulk and Vortices with half-integer winding numbers confined to the edge.
Abstract: We provide a simple explanation of complex magnetic patterns observed in ferromagnetic nanostructures. To this end we identify elementary topological defects in the field of magnetization: ordinary vortices in the bulk and vortices with half-integer winding numbers confined to the edge. Domain walls found in experiments and numerical simulations in strips and rings are composite objects containing two or more of the elementary defects.

157 citations

Network Information
Related Topics (5)
Superconductivity
71.9K papers, 1.3M citations
81% related
Vortex
72.3K papers, 1.3M citations
78% related
Hamiltonian (quantum mechanics)
48.6K papers, 1M citations
77% related
Ferromagnetism
55K papers, 1.2M citations
77% related
Magnetization
107.8K papers, 1.9M citations
76% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20215
20202
20196
20182
20162
20153