Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

Kramer, R. B. G.; Silhanek, Alejandro; Gillijns, Werner; Moshchalkov, Victor

doi:10.1103/physrevx.1.021004

Cited by 21 publications

(24 citation statements)

References 29 publications

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“…Similar pair formation has been observed by Kramer et al 29,. but in a system of Co/Pt multilayer disks with out-of-plane magnetisation, where spontaneous vortex-antivortex pairs were expected.…”

Section: Resultssupporting

confidence: 90%

Reconfigurable superconducting vortex pinning potential for magnetic disks in hybrid structures

Marchiori

Curran

Kim

et al. 2017

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High resolution scanning Hall probe microscopy has been used to directly visualise the superconducting vortex behavior in hybrid structures consisting of a square array of micrometer-sized Py ferromagnetic disks covered by a superconducting Nb thin film. At remanence the disks exist in almost fully flux-closed magnetic vortex states, but the observed cloverleaf-like stray fields indicate the presence of weak in-plane anisotropy. Micromagnetic simulations suggest that the most likely origin is an unintentional shape anisotropy. We have studied the pinning of added free superconducting vortices as a function of the magnetisation state of the disks, and identified a range of different phenomena arising from competing energy contributions. We have also observed clear differences in the pinning landscape when the superconductor and the ferromagnet are electron ically coupled or insulated by a thin dielectric layer, with an indication of non-trivial vortex-vortex interactions. We demonstrate a complete reconfiguration of the vortex pinning potential when the magnetisation of the disks evolves from the vortex-like state to an onion-like one under an in-plane magnetic field. Our results are in good qualitative agreement with theoretical predictions and could form the basis of novel superconducting devices based on reconfigurable vortex pinning sites.

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Section: Resultssupporting

confidence: 90%

Reconfigurable superconducting vortex pinning potential for magnetic disks in hybrid structures

Marchiori

Curran

Kim

et al. 2017

Sci Rep

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“…In previous works [26][27][28], we have demonstrated that the SSM technique is capable of extracting useful information of individual vortex dynamics with single-vortex resolution. Here we benefit from the MD simulation to analyze the vortex trajectories at much smaller scales.…”

Section: Trajectories Of a Single Vortexmentioning

confidence: 97%

Closer look at the low-frequency dynamics of vortex matter using scanning susceptibility microscopy

et al. 2014

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Using scanning susceptibility microscopy, we shed light on the dynamics of individual superconducting vortices and examine the hypotheses of the phenomenological models traditionally used to explain the macroscopic ac electromagnetic properties of superconductors. The measurements, carried out on a 2H-NbSe 2 single crystal at relatively high temperature (T = 6.8 K), show a linear amplitude dependence of the global ac susceptibility for excitation amplitudes between 0.3 and 2.6 Oe. We observe that the low amplitude response, typically attributed to the oscillation of vortices in a potential well defined by a single, relaxing, Labusch constant, actually corresponds to strongly nonuniform vortex shaking. This is particularly pronounced in the field-cooled disordered phase, which undergoes a dynamic reorganization above 0.8 Oe as evidenced by the healing of lattice defects and a more uniform oscillation of vortices. These observations are corroborated by molecular dynamics simulations when choosing the microscopic input parameters from the experiments. The theoretical simulations allow us to reconstruct the vortex trajectories, providing deeper insight into the thermally induced hopping dynamics and the vortex lattice reordering.

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“…The main advantage of the present approach with respect to the previous one is that no vortex-antivortex pairs are created due to inhomogeneous fields [25][26][27][28] and hence a more straighforward analysis, closer to the theoretical prediction, can be performed. In addition, while in Ref.…”

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confidence: 99%

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

et al. 2015

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In 1976 Larkin and Ovchinnikov [Sov. Phys. JETP 41, 960 (1976)] predicted that vortex matter in superconductors driven by an electrical current can undergo an abrupt dynamic transition from a flux-flow regime to a more dissipative state at sufficiently high vortex velocities. Typically this transition manifests itself as a large voltage jump at a particular current density, so-called instability current density J * , which is smaller than the depairing current. By tuning the effective pinning strength in Al films, using an artificial periodic pinning array of triangular holes, we show that a unique and well defined instability current density exists if the pinning is strong, whereas a series of multiple voltage transitions appear in the relatively weaker pinning regime. This behavior is consistent with time-dependent Ginzburg-Landau simulations, where the multiple-step transition can be unambiguously attributed to the progressive development of vortex chains and subsequently phase-slip lines. In addition, we explore experimentally the magnetic braking effects, caused by a thick Cu layer deposited on top of the superconductor, on the instabilities and the vortex ratchet effect.

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Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

Cited by 21 publications

References 29 publications

Reconfigurable superconducting vortex pinning potential for magnetic disks in hybrid structures

Reconfigurable superconducting vortex pinning potential for magnetic disks in hybrid structures

Closer look at the low-frequency dynamics of vortex matter using scanning susceptibility microscopy

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

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