Pinning-Induced Formation of Vortex Clusters and Giant Vortices in Mesoscopic Superconducting Disks

Grigorieva, I. V.; Escoffier, Walter; Misko, V. R.; Baelus, B. J.; Peeters, F. M.; Vinnikov, L. Ya.; Dubonos, S. V.

doi:10.1103/physrevlett.99.147003

Cited by 83 publications

(88 citation statements)

References 23 publications

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“…Comparing the spectrum (29) with the branches obtained from the direct numerical analysis of the eigenvalue problem (11), (31) one can see that the perturbation method provides a reasonable description of the energy spectrum behavior in a wide range of the impact parameters. As one would expect, the perturbation procedure fails for small impact parameters | b | ≪ R. Contrary to the CdGM case the spectrum branch (29) does not cross the Fermi level, and the minigap in the quasiparticle spectrum ∆ min = ε(R) grows with the increase in the cylinder radius R (see Fig.…”

Section: B Solution For Large Impact Parameters |B| > Rmentioning

confidence: 94%

Electronic structure of vortices pinned by columnar defects

2009

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The electronic structure of a vortex line trapped by an insulating columnar defect in a type-II superconductor is analysed within the Bogolubov-de Gennes theory. For quasiparticle trajectories with small impact parameters defined with respect to the vortex axis the normal reflection of electrons and holes at the defect surface results in the formation of an additional subgap spectral branch. The increase in the impact parameter at this branch is accompanied by the decrease of the excitation energy. When the impact parameter exceeds the radius of the defect this branch transforms into the Caroli-de Gennes-Matricon one. As a result, the minigap in the quasiparticle spectrum increases with the increase in the defect radius. The scenario of the spectrum transformation is generalized for the case of arbitrary vorticity.

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Section: B Solution For Large Impact Parameters |B| > Rmentioning

confidence: 94%

Electronic structure of vortices pinned by columnar defects

2009

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“…However, MQVs are of interest since under certain circumstances, the interaction between vortices is not purely repulsive and can support multi-vortex bound states, at least as metastable defects. This can happen, for instance, in type-II mesoscopic superconductors, where MQVs have been predicted [15] and experimentally observed [16][17][18][19]. In addition, it has been argued that MQVs are expected to be energetically stable in multicomponent superconductors [20,21] and in chiral p-wave superconductors [22,23].…”

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confidence: 95%

Multiply Quantized Vortices in Fermionic Superfluids: Angular Momentum, Unpaired Fermions, and Spectral Asymmetry

et al. 2017

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We compute the orbital angular momentum Lz of an s-wave paired superfluid in the presence of an axisymmetric multiply quantized vortex. For vortices with winding number |k| > 1, we find that in the weak-pairing BCS regime Lz is significantly reduced from its value N k/2 in the Bose-Einstein condensation (BEC) regime, where N is the total number of fermions. This deviation results from the presence of unpaired fermions in the BCS ground state, which arise as a consequence of spectral flow along the vortex sub-gap states. We support our results analytically and numerically by solving the Bogoliubov-de-Gennes equations within the weak-pairing BCS regime.Quantized vortices are a hallmark of superfluids (SFs) and superconductors. These topological defects form in response to external rotation or magnetic field and play a key role in understanding a broad spectrum of phenomena, such as the Berezinskii-Kosterlitz-Thouless transition in two-dimensional (2D) SFs [1,2], superconductor/insulator transitions [3][4][5], turbulence [6], and dissipation [7,8]. In fermionic s-wave paired states, the structure of the ground state and low lying excitations of an axisymmetric singly quantized vortex has been established through analytical and numerical studies in both the strong-pairing regime (where the SF phase is understood as a Bose-Einstein condensate (BEC) of bosonic molecules) and in the weak-pairing Bardeen Cooper Schrieffer (BCS) regime. In the BEC regime, the microscopic Gross-Pitaevskii equation provides a reliable framework [9,10], while in the BCS regime the (selfconsistent) Bogoliubov-deGennes (BdG) theory is key in identifying the structure of the ground state [11,12] and the spectrum of sub-gap fermionic excitations [13].Multiply quantized vortices (MQVs) have however not received much attention. Generically in a homogeneous bulk system, the logarithmic repulsion between vortices, which scales as the square of the vortex winding number k, energetically favors an instability of a multiply quantized vortex into separated elementary unit vortices [14]. However, MQVs are of interest since under certain circumstances, the interaction between vortices is not purely repulsive and can support multi-vortex bound states, at least as metastable defects. This can happen, for instance, in type-II mesoscopic superconductors, where MQVs have been predicted [15] and experimentally observed [16][17][18][19]. In addition, it has been argued that MQVs are expected to be energetically stable in multicomponent superconductors [20,21] and in chiral p-wave superconductors [22,23]. In fermionic SFs, a doubly quantized vortex was predicted [24] and observed in 3 He-A [25]. It has further been argued that fast rotating Fermi gases trapped in an anharmonic potential will support an MQV state [26][27][28]. Similar vortex states have been created in rotating BEC experiments [29][30][31][32].Surprisingly, as we demonstrate in this Letter, there is a fundamental difference between a singly quantized vortex (|k| = 1) and an MQV (|k| > 1) in a wea...

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“…Here we present the first study on vortex pinning in hyperbolic 2D tesselations. In mesoscopic superconductors, the geometry of a sample and/or its underlying pinning has a strong impact on its vortex pattern; for example, the appearance of vortex concentric "shells" [9][10][11] in mesoscopic disks, which can even merge into so-called giant vortices 12 in very small disks. In symmetric polygons, e.g., triangles and squares, vortices tend to form patterns with the symmetry of the polygon boundary.…”

Section: Introductionmentioning

confidence: 99%

Magnetic flux pinning in superconductors with hyperbolic-tessellation arrays of pinning sites

Nori

2012

Phys. Rev. B

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We study magnetic flux interacting with arrays of pinning sites (APS) placed on vertices of hyperbolic tesselations (HT). We show that, due to the gradient in the density of pinning sites, HT APS are capable of trapping vortices for a broad range of applied magnetic fluxes. Thus, the penetration of magnetic field in HT APS is essentially different from the usual scenario predicted by the Bean model. We demonstrate that, due to the enhanced asymmetry of the surface barrier for vortex entry/exit, this HT APS could be used as a "capacitor" to store magnetic flux.

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Pinning-Induced Formation of Vortex Clusters and Giant Vortices in Mesoscopic Superconducting Disks

Cited by 83 publications

References 23 publications

Electronic structure of vortices pinned by columnar defects

Electronic structure of vortices pinned by columnar defects

Multiply Quantized Vortices in Fermionic Superfluids: Angular Momentum, Unpaired Fermions, and Spectral Asymmetry

Magnetic flux pinning in superconductors with hyperbolic-tessellation arrays of pinning sites

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