Bound vortex dipoles generated at pinning centres by Meissner current

Ge, Jun‐Yi; Gutiérrez, J.; Gladilin, V. N.; Devreese, Jozef T.; Moshchalkov, Victor

doi:10.1038/ncomms7573

Cited by 28 publications

(30 citation statements)

References 43 publications

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“…The source materials are 99.999%-pure Pb and 99.9999%-pure Ge. The external magnetic field is applied perpendicularly to the sample surface, and the vortex configurations are visualized directly using a-low temperature SHPM (with a magnetic-field resolution of 10 −5 T and a temperature stability better than 1 mK) [35,36]. All the SHPM images of vortex patterns in our measurements are obtained by lifting the Hall cross about 500-800 nm above the sample surface at T = 4.25 K.…”

Section: Sample and Experimentsmentioning

confidence: 99%

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

Xue

et al. 2017

Phys. Rev. B

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We investigate the degeneracy of the superconducting vortex matter ground state by directly visualizing the vortex configurations in a kagome lattice of elongated antidots via scanning Hall probe microscopy. The observed vortex patterns, at specific applied magnetic fields, are in good agreement with the configurations obtained using time-dependent Ginzburg-Landau simulations. Both results indicate that the long-range interaction in this nanostructured superconductor is unable to lift the degeneracy between different vortex states and the pattern formation is mainly ruled by the nearest-neighbor interaction. This simplification makes it possible to identify a set of simple rules characterizing the vortex configurations. We demonstrate that these rules can explain both the observed vortex distributions and the magnetic-field-dependent degree of degeneracy.

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Section: Sample and Experimentsmentioning

confidence: 99%

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

Xue

et al. 2017

Phys. Rev. B

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“…Thus, we demonstrate that the vortex-antivortex magnetic dipoles recently observed with the scanning Hall microscope 18,19 originate from the stationary current flow around the pinning center. The spatial profile of the non-uniform magnetic field induced by the current contains the explicit information about the shape of the defect.…”

Section: (2)mentioning

confidence: 99%

“…Thus, our simple model based on the stationary current theory fully explains the formation of the vortex-antivortex pairs recently observed with the scanning Hall microscope. 18,19 Note that the finite sample thickness h and the finite distance z 0 between the tip and the surface of the superconductor does not lead to any qualitative changes of the B z (r, ϕ) profiles [see Fig. 2(c) and 2(d)].…”

Section: (2)mentioning

confidence: 99%

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Magnetic mapping of defects in type-II superconductors

Миронов

Devizorova

Clergerie

et al. 2016

Applied Physics Letters

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Recently it was discovered that the non-uniform Meissner current flowing around the pinning sites in the type-II superconductor induces the unconventional vortex-antivortex pairs with the non-quantized magnetic flux [J.-Y. Ge, J. Gutierrez, V. N. Gladilin, J. T. Devreese, and V. V. Moshchalkov, Nat. Commun. 6, 6573 (2015)]. Here we provide the theory of this phenomenon showing that the vortex-like structures originate from the perturbation of the current streamlines by the non-superconducting defect, which results in the generation of the localized magnetic field. The position and the shape of such vortex dipoles are shown to be very sensitive to the defect form. Thus, applying the external magnetic field or current to the superconductor and using, e.g., the high-resolution scanning Hall microscope to measure the stray magnetic field one can plot the map containing the information about the position of the defects and their shape.The control of the Abrikosov vortex pinning is one of the corner-stone problems in the physics of superconducting systems. 1,2 The reduction of the vortex mobility by a lattice of the pinning centers allows to damp the energy dissipation and substantially increase the critical current, 3-7 which is extremely important for application of superconductors in electronics. During the last decades it became possible to create both low-and high-temperature superconductors with various types of natural and artificial defects (holes, 8-10 grain boundaries, 11 nanorods, 12-14 imbedded nanoparticles, 15 surface grades, 16 controllable lattice transformations, 17 etc.) which are shown to be effective barriers for the vortex motion. The corresponding enhancement of the critical current appears to be very sensitive to the particular shape and the spatial distribution of the pinning centers. This aims the efforts of both theoreticians and experimentalists at the engineering of the efficient pinning potentials and the extensive study of the magnetic flux behavior simultaneously affected by the pinning sites and the transport current.Recently the magnetic field induced by the Meissner current flowing around the pinning sites was measured with the high-resolution scanning Hall microscope. 18,19 It was found that the magnetic contrast near the defects reminds the one for the pair of vortex and antivortex. Interestingly, the magnetic flux carried by each pole of such "vortex dipole" is not quantized and depends on current. To explain this effect the authors have performed sophisticated numerical simulations based on the time-dependent Ginzburg-Landau equation accounting the non-uniform profile of the Meissner current. Here we provide the simple explanation of this phenomenon within the stationary currents theory. It is based on the fact that each defect being impervious for the Cooper pairs perturbs the streamlines of the superconducting current which gives rise to the well-localized stray magnetic field. Our analysis clearly shows that the formation of the vortex dipoles is not specific to the Meissner s...

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“…1b. The free energy is calculated for the corresponding stationary solutions of the time-dependent GinzburgLandau (TDGL) equations (see [42,43] for details of the used formalism and numerical approach). The TDGL simulations are performed for a periodic system with a supercell size of 13.6 × 13.6 µm 2 (170 × 170 grid points) and the same geometry and distriution of antidots as that in the experimental sample.…”

Section: Simulationsmentioning

confidence: 99%

Direct visualization of vortex ice in a nanostructured superconductor

Gladilin

Tempere

et al. 2017

Phys. Rev. B

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Artificial ice systems have unique physical properties promising for potential applications. One of the most challenging issues in this field is to find novel ice systems that allows a precise control over the geometries and many-body interactions. Superconducting vortex matter has been proposed as a very suitable candidate to study artificial ice, mainly due to availability of tunable vortex-vortex interactions and the possibility to fabricate a variety of nanoscale pinning potential geometries. So far, a detailed imaging of the local configurations in a vortex-based artificial ice system is still lacking. Here we present a direct visualization of the vortex ice state in a nanostructured superconductor. By using the scanning Hall probe microscopy, a large area with the vortex ice ground state configuration has been detected, which confirms the recent theoretical predictions for this new ice system. Besides the defects analogous to artificial spin ice systems, other types of defects have been visualized and identified. We also demonstrate the possibility to realize different types of defects by varying the magnetic field.

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Bound vortex dipoles generated at pinning centres by Meissner current

Cited by 28 publications

References 43 publications

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

Magnetic mapping of defects in type-II superconductors

Direct visualization of vortex ice in a nanostructured superconductor

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