“Unusual commensurability effects in quasiperiodic pinning arrays induced by local inhomogeneities of the pinning site density”. Bothner D, Seidl R, Misko VR, Kleiner R, Koelle D, Kemmler M, Superconductor science and technology 27, 065002 (2014). http://doi.org/10.1088/0953-2048/27/6/065002
Abstract: We experimentally investigate the magnetic field dependence of the critical current I-c(B) of superconducting niobium thin films patterned with periodic and quasiperiodic antidot arrays on the submicron scale. For this purpose we monitor current-voltage characteristics at different values of B and temperature T. We investigate samples with antidots positioned at the vertices of two different tilings with quasiperiodic symmetry, namely the Shield Tiling and the Tuebingen Triangle Tiling. For reference we investigate a sample with a triangular antidot lattice. We find modulations of the critical current for both quasiperiodic tilings, which have partly been predicted by numerical simulations but not observed in experiments yet. The particularity of these commensurability effects is that they correspond to magnetic field values slightly above an integer multiple of the matching field. The observed matching effects can be explained by the caging of interstitial vortices in quasiperiodically distributed cages and the formation of symmetry-induced giant vortices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.878
Times cited: 7
DOI: 10.1088/0953-2048/27/6/065002
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“Using self-driven microswimmers for particle separation”. Yang W, Misko VR, Nelissen K, Kong M, Peeters FM, Soft matter 8, 5175 (2012). http://doi.org/10.1039/c2sm07382j
Abstract: Microscopic self-propelled swimmers capable of autonomous navigation through complex environments provide appealing opportunities for localization, pick-up and delivery of micro and nanoscopic objects. Inspired by motile cells and bacteria, man-made microswimmers have been fabricated, and their motion in patterned surroundings has been experimentally studied. We propose to use self-driven artificial microswimmers for the separation of binary mixtures of colloids. We revealed different regimes of separation, including one with a velocity inversion. Our findings could be of use for various biological and medical applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.889
Times cited: 45
DOI: 10.1039/c2sm07382j
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“Vortex configurations in mesoscopic superconducting triangles: finite-size and shape effects”. Zhao HJ, Misko VR, Peeters FM, Dubonos G, Oboznov V, Grigorieva IV, Europhysics letters 83, 17008 (2008). http://doi.org/10.1209/0295-5075/83/17008
Abstract: Triangular-shaped mesoscopic superconductors are consistent with the symmetry of the Abrikosov vortex lattice resulting in a high stability of vortex patterns for commensurate vorticities. However, for non-commensurate vorticities, vortex configurations in triangles are not compatible with the sample shape. Here we present the first direct observation of vortex configurations in ìm-sized niobium triangles using the Bitter decoration technique, and we analyze the vortex states in triangles by analytically solving the London equations and performing molecular-dynamics simulations. We found that filling rules with increasing vorticity can be formulated for triangles in a similar way as for mesoscopic disks where vortices form shells.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 29
DOI: 10.1209/0295-5075/83/17008
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“Vortex configurations with non-monotonic interaction”. Zhao HJ, Misko VR, Peeters FM, Physica: C : superconductivity 479, 130 (2012). http://doi.org/10.1016/j.physc.2011.12.033
Abstract: The pattern formation of the vortex states with non-monotonic inter-vortex interaction is investigated. Our applied model has a short-range repulsive (r < r(c)) and long-range attractive (r > r(c)) potential. We numerically calculate the stable states using molecular-dynamics simulations. The obtained vortex patterns are comparable with the vortices states in low kappa type-II superconductors and recently discovered "type-1.5'' superconductors. We also analyze the nearest neighbor distribution of the obtained patterns. (C) 2012 Published by Elsevier B.V.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 9
DOI: 10.1016/j.physc.2011.12.033
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“Vortex quantum tunneling versus thermal activation in ultrathin superconducting nanoislands”. Pogosov WV, Misko VR, Physical review : B : condensed matter and materials physics 85, 224508 (2012). http://doi.org/10.1103/PhysRevB.85.224508
Abstract: We consider two possible mechanisms for single-vortex fluctuative entry/exit through the surface barrier in ultrathin superconducting disk-shaped nanoislands made of Pb and consisting of just a few monoatomic layers, which can be fabricated using modern techniques. We estimate tunneling probabilities and establish criteria for the crossover between these two mechanisms depending on magnetic field and system sizes. For the case of vortex entry, quantum tunneling dominates on the major part of the temperature/flux phase diagram. For the case of vortex exit, thermal activation turns out to be more probable. This nontrivial result is due to the subtle balance between the barrier height and width, which determine rates of the thermal activation and quantum tunneling, respectively.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 2
DOI: 10.1103/PhysRevB.85.224508
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“Vortex states in a mescopic superconducting triangle”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, Physica C-Superconductivity And Its Applications 369, 361 (2002). http://doi.org/10.1016/S0921-4534(01)01277-1
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.404
Times cited: 14
DOI: 10.1016/S0921-4534(01)01277-1
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“Vortex states in a multi-conoid superconducting nanosized bridge”. Misko VR, Fomin VM, Devreese JT, Physica C-Superconductivity And Its Applications 369, 356 (2002). http://doi.org/10.1016/S0921-4534(01)01276-X
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.404
Times cited: 1
DOI: 10.1016/S0921-4534(01)01276-X
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“Vortex states in mesoscopic superconducting squares: formation of vortex shells”. Zhao HJ, Misko VR, Peeters FM, Oboznov V, Dubonos SV, Grigorieva IV, Physical review : B : condensed matter and materials physics 78, 104517 (2008). http://doi.org/10.1103/PhysRevB.78.104517
Abstract: We analyze theoretically and experimentally vortex configurations in mesoscopic superconducting squares. Our theoretical approach is based on the analytical solution of the London equation using Green's-function method. The potential-energy landscape found for each vortex configuration is then used in Langevin-type molecular-dynamics simulations to obtain stable vortex configurations. Metastable states and transitions between them and the ground state are analyzed. We present our results of the first direct visualization of vortex patterns in micrometer-sized Nb squares, using the Bitter decoration technique. We show that the filling rules for vortices in squares with increasing applied magnetic field can be formulated, although in a different manner than in disks, in terms of formation of vortex “shells”.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 39
DOI: 10.1103/PhysRevB.78.104517
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“Vortex transport in a channel with periodic constrictions”. Kapra AV, Vodolazov DY, Misko VR, Superconductor science and technology 26, 095010 (2013). http://doi.org/10.1088/0953-2048/26/9/095010
Abstract: By numerically solving the time-dependent Ginzburg-Landau equations in a type-II superconductor, characterized by a critical temperature T-c1, and the coherence length xi(1), with a channel formed by overlapping rhombuses (diamond-like channel) made of another type-II superconductor, characterized, in general, by different T-c2 and xi(2), we investigate the dynamics of driven vortex matter for varying parameters of the channel: the width of the neck connecting the diamond cells, the cell geometry, and the ratio between the coherence lengths in the bank and the channel. We analyzed samples with periodic boundary conditions (which we call 'infinite' samples) and finite-size samples (with boundaries for vortex entry/exit), and we found that by tuning the channel parameters, one can manipulate the vortex dynamics, e.g., change the transition from flux-pinned to flux-flow regime and tune the slope of the IV-curves. In addition, we analyzed the effect of interstitial vortices on these characteristics. The critical current of this device was studied as a function of the applied magnetic field, j(c)(H). The function j(c)(H) reveals a striking commensurability peak, in agreement with recent experimental observations. The obtained results suggest that the diamond channel, which combines the properties of pinning arrays and flux-guiding channels, can be a promising candidate for potential use in devices controlling magnetic flux motion.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.878
Times cited: 2
DOI: 10.1088/0953-2048/26/9/095010
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