| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
- Babaev, Egor, et al.
(författare)
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Magnetic Field Delocalization and Flux Inversion in Fractional Vortices in Two-Component Superconductors
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:23
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that, in contrast with the single-component Abrikosov vortex, in two-component superconductors vortex solutions with an exponentially screened magnetic field exist only in exceptional cases: in the case of vortices carrying an integer number of flux quanta and in a special parameter limit for half-quantum vortices. For all other parameters, the vortex solutions have a delocalized magnetic field with a slowly decaying tail. Furthermore, we demonstrate a new effect which is generic in two-component systems but has no counterpart in single-component systems: on exactly half of the parameter space of the U(1)xU(1) Ginzburg-Landau model, the magnetic field of a generic fractional vortex inverts its direction at a certain distance from the vortex core.
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| 3. |
- Babaev, Egor, et al.
(författare)
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Type-1.5 Superconducting State from an Intrinsic Proximity Effect in Two-Band Superconductors
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:6, s. 067003-
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Tidskriftsartikel (refereegranskat)abstract
- We show that in multiband superconductors, even an extremely small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vortices by producing long-range intervortex attraction. This type of vortex interaction results in an unusual response to low magnetic fields leading to phase separation into domains of two-component Meissner states and vortex droplets.
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| 4. |
- Benfenati, Andrea, et al.
(författare)
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Magnetic signatures of domain walls in s plus is and s plus id superconductors : Observability and what that can tell us about the superconducting order parameter
- 2020
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 101:5
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Tidskriftsartikel (refereegranskat)abstract
- One of the defining features of spontaneously broken time-reversal symmetry (BTRS) is the existence of domain walls, the detection of which would be strong evidence for such systems. There is keen interest in BTRS currently, in part, due to recent muon spin rotation experiments, which have pointed towards Ba1-xKxFe2As2 exhibiting a remarkable case of s-wave superconductivity with spontaneously broken time-reversal symmetry. A key question, however, is how to differentiate between the different theoretical models which describe such a state. Two particularly popular choices of model are s + is and s + id superconducting states. In this paper, we obtain solutions for domain walls in s + is and s + id systems, including the effects of lattice anisotropies. We show that, in general, both models exhibit spontaneous magnetic fields that extend along the entire length of the domain wall. We demonstrate the qualitative difference between the magnetic signatures of s + is and s + id domain walls and propose a procedure to extract the superconducting pairing symmetry from the magnetic-field response of domain walls.
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| 5. |
- Carlström, Johan, et al.
(författare)
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Type-1.5 superconductivity in multiband systems : Effects of interband couplings
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 83:17, s. 174509-
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to single-component superconductors, which are described at the level of Ginzburg-Landau theory by a single parameter kappa and are divided in type-I kappa < 1/root 2 and type-II kappa > 1/root 2 classes, two-component systems in general possess three fundamental length scales and have been shown to possess a separate "type-1.5" superconducting state. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges, and therefore should form clusters in low magnetic fields. In this work we investigate the appearance of type-1.5 superconductivity and the interpretation of the fundamental length scales in the case of two active bands with substantial interband couplings such as intrinsic Josephson coupling, mixed gradient coupling, and density-density interactions. We show that in the presence of substantial intercomponent interactions of the above types the system supports type-1.5 superconductivity with fundamental length scales being associated with the mass of the gauge field and two masses of normal modes represented by mixed combinations of the density fields.
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| 6. |
- Garaud, Julien, et al.
(författare)
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Chiral CP2 skyrmions in three-band superconductors
- 2013
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 87:1, s. 014507-
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Tidskriftsartikel (refereegranskat)abstract
- 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 CP2 topological invariant, in models for three-component 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.
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| 7. |
- Harland, Derek, et al.
(författare)
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Isospinning hopfions
- 2013
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Ingår i: Journal of Physics A. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 46:22, s. 225402-
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Tidskriftsartikel (refereegranskat)abstract
- The problem of constructing internally rotating solitons of fixed angular frequency omega in the Faddeev-Skyrme model is reformulated as a variational problem for an energy-like functional, called pseudoenergy, which depends parametrically on omega. This problem is solved numerically using a gradient descent method, without imposing any spatial symmetries on the solitons, and the dependence of the solitons' energy on omega, and on their conserved total isospin J, studied. It is found that, generically, the shape of a soliton is independent of omega, and that its size grows monotonically with omega. A simple elastic rod model of time-dependent hopfions is developed which, despite having only one free parameter, accounts well for most of the numerical results.
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| 8. |
- Harland, Derek, et al.
(författare)
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Skyrmion crystals stabilized by ω-mesons
- 2024
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media Deutschland GmbH. - 1126-6708 .- 1029-8479. ; 2024:6
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the ground state crystalline structure of nuclear matter in the ω-meson variant of the Skyrme model. After minimizing energy with respect to variations of both the Skyrme field and the period lattice, we find four distinct periodic solutions which are similar to those found in the standard Skyrme model. We use these crystals to calculate coefficients in the Bethe-Weizsäcker semi-empirical mass formula and the compression modulus of infinite nuclear matter, and find a significant improvement as compared with other variants of the Skyrme model.
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| 9. |
- Speight, Martin, et al.
(författare)
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Chiral p-wave superconductors have complex coherence and magnetic field penetration lengths
- 2019
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 100:17
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Tidskriftsartikel (refereegranskat)abstract
- We show that in superconductors that break time-reversal symmetry and have anisotropy, such as p + ip materials, all order parameters and magnetic modes are mixed. Excitation of the gap fields produces an excitation of the magnetic field and vice versa. Correspondingly, the long-range decay of the magnetic field and order parameter is in general given by the same exponent. Thus, one cannot characterize p + ip superconductors by the usual coherence and magnetic field penetration lengths. Instead, the system has normal modes that are associated with linear combinations of magnetic fields, moduli of and phases of the order-parameter components. Each such normal mode has its own decay length that plays the role of a hybridized coherence/magnetic field penetration length. On a large part of the parameter space, these exponents are complex. Therefore, the system in general has damped oscillatory decay of the magnetic field accompanied by damped oscillatory variation of the order-parameter fields.
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| 10. |
- Speight, Martin, et al.
(författare)
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Magnetic field behavior in s plus is and s plus id superconductors : Twisting of applied and spontaneous fields
- 2021
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 104:17
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Tidskriftsartikel (refereegranskat)abstract
- We consider magnetic field screening and spontaneous magnetic fields in s + is and s + id superconductors both analytically and numerically. We show that in general, the linearized model couples the moduli of order parameters to the magnetic modes. This causes magnetic field screening that does not follow the standard exponential law and hence cannot be characterized by a single length scale: the London penetration length. We also demonstrate that the resulting linear mixed modes, correctly predict spontaneous fields and their orientation. We show that these mixed modes cause external fields to decay nonmonotonically in the bulk. This is observed as the magnetic field twisting direction, up to an angle of pi /2, as it decays in the nonlinear model. Finally, we demonstrate that there are two nondegenerate domain wall solutions for any given parameter set. These are distinguished by either clockwise or anticlockwise interpolation of the intercomponent phase difference, each producing a different solution for the other fields. However, only domain wall solutions ins + id systems exhibit magnetic field twisting.
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