Magnetic vortices

Recently vortex coalescence was reported in superconducting Sr2RuO4 by several experimental groups for fields applied along the c-axis. We argue that Sr2RuO4 is a type-1.5 superconductor with long-range attractive, short-range repulsive intervortex interaction. The type-1.5 behavior stems from an interplay of the two orbital degrees of freedom describing this chiral superconductor together with the multiband nature of the superconductivity. These multiple degrees of freedom give rise to multiple coherence lengths, some of which are larger and some smaller than the magnetic field penetration length, resulting in nonmonotonic intervortex forces.

A conventional superconductor is described by a single complex order parameter field which has two fundamental length scales, the magnetic field penetration depth λ and the coherence length ξ. Their ratio κ determines the response of a superconductor to an external field, sorting them into two categories as follows; type-I when κ < 1/ √ 2 and type-II when κ > 1/ √ 2. We overview here multicomponent systems which can possess three or more fundamental length scales and allow a separate "type-1.5" superconducting state when, e.g. in two-component case ξ1 < √ 2λ < ξ2. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges. As a consequence the system should form an additional Semi-Meissner state which properties we discuss below. In that state vortices form clusters in low magnetic fields. Inside the cluster one of the component is depleted and the superconductorto-normal interface has negative energy. In contrast the current in second component is mostly concentrated on the cluster's boundary, making the energy of this interface positive. Here we briefly overview recent developments in Ginzburg-Landau and microscopic descriptions of this state.

Symmetry classification of the magnetic vortices and skyrmions has been suggested. Relation between symmetry based predictions and direct calculation has been shown. It was shown that electric dipole moment of the vortex is located inside the small vortex core. The antivortices and antiskyrmions do not carry the total core electric dipole induced by the flexomagnetoelectric interaction in the hexoctahedral cubic crystal. The volumetric bound electric charge is distributed around the core. Switching of the core electric dipole direction produces the switching of the core magnetization or vortex chirality and vice versa. The vortices and skyrmions with time-invariant enantiomorphism have two degenerative states: clockwise and counterclockwise state.

We demonstrate existence of non-pairwise interaction forces between vortices in multicomponent and layered superconducting systems. That is, in contrast to most common models, the interactions in a group of such vortices is not a universal superposition of Coulomb or Yukawa forces. Next we consider the properties of vortex clusters in Semi-Meissner state of type-1.5 two-component superconductors. We show that under certain condition non-pairwise forces can contribute to formation of very complex vortex states in type-1.5 regimes. arXiv:1101.4599v2 [cond-mat.supr-con]

It is shown that under certain conditions, three-component superconductors (and in particular three-band systems) allow stable topological defects different from vortices. We demonstrate the existence of these excitations, characterized by a CP 2 topological invariant, in models for threecomponent superconductors with broken time reversal symmetry. We term these topological defects "chiral GL (3) skyrmions", where "chiral" refers to the fact that due to broken time reversal symmetry, these defects come in inequivalent left-and right-handed versions. In certain cases these objects are energetically cheaper than vortices and should be induced by an applied magnetic field. In other situations these skyrmions are metastable states, which can be produced by a quench. Observation of these defects can signal broken time reversal symmetry in three-band superconductors or in Josephson-coupled bilayers of s± and s-wave superconductors.

Observability of half-quantum vortices and skyrmions in p-wave superconductors is an outstanding open question. Under the most common conditions, fractional flux vortices are not thermodynamically stable in bulk samples. Here we show that in chiral p-wave superconductors, there is a regime where, in contrast lattices of integer flux vortices are not thermodynamically stable. Instead skyrmions made of spatially separated half-quantum vortices are the topological defects produced by an applied external field.

Recently vortex coalescence was reported in superconducting Sr2RuO4 by several experimental groups for fields applied along the c-axis. We argue that Sr2RuO4 is a type-1.5 superconductor with long-range attractive, short-range repulsive intervortex interaction. The type-1.5 behavior stems from an interplay of the two orbital degrees of freedom describing this chiral superconductor together with the multiband nature of the superconductivity. These multiple degrees of freedom give rise to multiple coherence lengths, some of which are larger and some smaller than the magnetic field penetration length, resulting in nonmonotonic intervortex forces.

A conventional superconductor is described by a single complex order parameter field which has two fundamental length scales, the magnetic field penetration depth λ and the coherence length ξ. Their ratio κ determines the response of a superconductor to an external field, sorting them into two categories as follows; type-I when κ < 1/ √ 2 and type-II when κ > 1/ √ 2. We overview here multicomponent systems which can possess three or more fundamental length scales and allow a separate "type-1.5" superconducting state when, e.g. in two-component case ξ1 < √ 2λ < ξ2. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges. As a consequence the system should form an additional Semi-Meissner state which properties we discuss below. In that state vortices form clusters in low magnetic fields. Inside the cluster one of the component is depleted and the superconductorto-normal interface has negative energy. In contrast the current in second component is mostly concentrated on the cluster's boundary, making the energy of this interface positive. Here we briefly overview recent developments in Ginzburg-Landau and microscopic descriptions of this state.

A conventional superconductor is described by a single complex order parameter field which has two fundamental length scales, the magnetic field penetration depth λ and the coherence length ξ. Their ratio κ determines the response of a superconductor to an external field, sorting them into two categories as follows; type-I when κ < 1/ √ 2 and type-II when κ > 1/ √ 2. We overview here multicomponent systems which can possess three or more fundamental length scales and allow a separate "type-1.5" superconducting state when, e.g. in two-component case ξ1 < √ 2λ < ξ2. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges. As a consequence the system should form an additional Semi-Meissner state which properties we discuss below. In that state vortices form clusters in low magnetic fields. Inside the cluster one of the component is depleted and the superconductorto-normal interface has negative energy. In contrast the current in second component is mostly concentrated on the cluster's boundary, making the energy of this interface positive. Here we briefly overview recent developments in Ginzburg-Landau and microscopic descriptions of this state.

A conventional superconductor is described by a single complex order parameter field which has two fundamental length scales, the magnetic field penetration depth λ and the coherence length ξ. Their ratio κ determines the response of a superconductor to an external field, sorting them into two categories as follows; type-I when κ < 1/ √ 2 and type-II when κ > 1/ √ 2. We overview here multicomponent systems which can possess three or more fundamental length scales and allow a separate "type-1.5" superconducting state when, e.g. in two-component case ξ1 < √ 2λ < ξ2. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges. As a consequence the system should form an additional Semi-Meissner state which properties we discuss below. In that state vortices form clusters in low magnetic fields. Inside the cluster one of the component is depleted and the superconductorto-normal interface has negative energy. In contrast the current in second component is mostly concentrated on the cluster's boundary, making the energy of this interface positive. Here we briefly overview recent developments in Ginzburg-Landau and microscopic descriptions of this state.

We show that three-band superconductors with broken time reversal symmetry allow magnetic flux-carrying stable topological solitons. They can be induced by fluctuations or quenching the system through a phase transition. It can provide an experimental signature of the time reversal symmetry breakdown.

We present a detailed analysis of classical solutions in the bosonic sector of the electroweak theory which describe vortices carrying a constant electric current I. These vortices exist for any value of the Higgs boson mass and for any weak mixing angle and in the zero current limit they reduce to Z strings. Their current is produced by the condensate of vector W bosons and typically it can attain billions of amperes. For large I the vortices show a compact condensate core of size ∼1/I, embedded into a region of size ∼I where the electroweak gauge symmetry is completely restored, followed by a transition zone where the Higgs field interpolates between the symmetric and broken phases. Outside this zone the fields are the same as for the ordinary electric wire. An analytic approximation of the large I solutions suggests that the current can be arbitrarily large, due to the scale invariance of the vector boson condensate. Finite vortex segments are likely to be perturbatively stable. ...

The team has already observed some unique configurations, and going forward, their further exploration promises to bring to light yet more magnetic beauty. [17] A tunnel junction is a device consisting of two conducting layers separated by an insulating layer. [16] A new low-power technique for detecting the spin of electrons in a non-magnetic system could aid the development of spintronics devices that work using ferroelectricity rather than ferromagnetism. [15] A combined team of researchers from the University of North Carolina at Chapel Hill and Kent State University has discovered an electrically neutral radical that can be used as a strong chemical reducing agent when excited by light. [14] In new research, scientists at the University of Minnesota used a first-of-its-kind device to demonstrate a way to control the direction of the photocurrent without deploying an electric voltage. [13] Brown University researchers have demonstrated for the first time a method of substantially changing the spatial coherence of light. [12] Researchers at the University of Central Florida have generated what is being deemed the fastest light pulse ever developed. [11] Physicists at Chalmers University of Technology and Free University of Brussels have now found a method to significantly enhance optical force. [10] Nature Communications today published research by a team comprising Scottish and South African researchers, demonstrating entanglement swapping and teleportation of orbital angular momentum 'patterns' of light. [9] While physicists are continually looking for ways to unify the theory of relativity, which describes large-scale phenomena, with quantum theory, which describes small-scale phenomena, computer scientists are searching for technologies to build the quantum computer using Quantum Information. In August 2013, the achievement of "fully deterministic" quantum teleportation, using a hybrid technique, was reported. On 29 May 2014, scientists announced a reliable way of transferring data by quantum teleportation. Quantum teleportation of data had been done before but with highly unreliable methods. The accelerating electrons explain not only the Maxwell Equations and the Special Relativity, but the Heisenberg Uncertainty Relation, the Wave-Particle Duality and the electron's spin also, building the Bridge between the Classical and Quantum Theories. The Planck Distribution Law of the electromagnetic oscillators explains the electron/proton mass rate and the Weak and Strong Interactions by the diffraction patterns. The Weak Interaction changes the diffraction patterns by moving the electric charge from one side to the other side of the diffraction pattern, which violates the CP and Time reversal symmetry. The diffraction patterns and the locality of the self-maintaining electromagnetic potential explains also the Quantum Entanglement, giving it as a natural part of the Relativistic Quantum Theory and making possible to build the Quantum Computer with the help of Quantum Information.

It is shown that under certain conditions, three-component superconductors (and in particular three-band systems) allow stable topological defects different from vortices. We demonstrate the existence of these excitations, characterized by a CP 2 topological invariant, in models for threecomponent superconductors with broken time reversal symmetry. We term these topological defects "chiral GL (3) skyrmions", where "chiral" refers to the fact that due to broken time reversal symmetry, these defects come in inequivalent left-and right-handed versions. In certain cases these objects are energetically cheaper than vortices and should be induced by an applied magnetic field. In other situations these skyrmions are metastable states, which can be produced by a quench. Observation of these defects can signal broken time reversal symmetry in three-band superconductors or in Josephson-coupled bilayers of s± and s-wave superconductors.