Vortex dynamics in regular arrays of asymmetric pinning centers

Zhu, Bei; Look, Lieve Van; Мощалков, В.В.; Zhao, Bo-Wei; Zhao, Z.X.

doi:10.1103/physrevb.64.012504

Cited by 33 publications

(27 citation statements)

References 16 publications

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“…30,31 Now let us consider the 2D problem of a lattice of inertial vortices interacting with a 2D array of asymmetric pinning sites, which can be modeled as two superposed square sublattices of strong and weak attractive potential. 12,13,15,16 The sublattices have a spacing d 0 ͑=1 here͒ and are shifted with respect to each other by a distance 0.36 d 0 , which is the same as the separation in the experimental sample. 15 All pinning centers are modeled by Gaussian potential wells with a decay length R p .…”

Section: B Sudden V Dc Reversal At Large I Rfmentioning

confidence: 99%

“…Either an array of triangular magnetic dots or an array of asymmetric antidotes can serve as pinning sites to trap the quantized flux lines to form a vortex array. [10][11][12][13][14][15][16][17][18][19][20][21] With a periodic and asymmetrical pinning potential, this vortex array rectifies the applied alternative current to produce dc voltage output V dc , just as what a diode does. The advantages of such a system are the following.…”

Section: Introductionmentioning

confidence: 99%

“…The advantages of such a system are the following. ͑1͒ By nature it is a two-dimensional ͑2D͒ multiparticle ratchet system, which contains a large amount of the vortex cells with long-range interactions between them, making it possible to observe rich physical phenomena here 12,13 which are different those in the case of single particle in a one-dimensional potential. For example, simulations demonstrate that molecular motors can cooperate in large groups, and the combination of a large number of interacting particles will lead to ineluctable dynamical phase transition and instabilities; 27,28 ͑2͒ strong rectification can be expected because the voltage is proportional to the number of the vortices when they move in a coherent way; and ͑3͒, the asymmetric potential can be tuned by changing the size and shape of the pinning sites, as well as the polarity of the vortices in the magnetic dot array.…”

Section: Introductionmentioning

confidence: 99%

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High-frequency vortex ratchet effect in a superconducting film with a nanoengineered array of asymmetric pinning sites

et al. 2010

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Vortex ratchet effect is investigated experimentally in the frequency range between 0.5 MHz and 2 GHz. The ratchet potential is provided by an array of about a quarter of a million nanoengineered asymmetric antidots in a Pb film. A square vortex lattice is stabilized at the first matching field, when each asymmetric antidot is occupied by a single vortex. We have found that ͑1͒ the transition from adiabatic to nonadiabatic cases occurring at about 1 MHz, above which the ratchet windows shift upwards with the applied frequency due to the fact that the time for a vortex to escape from the pinning potential is comparable to the period of the applied rf driving current I rf ; ͑2͒ a sudden V dc reversal at large I rf , which can be attributed to inertia effect; ͑3͒ the collective step-motor behavior in the MHz region, i.e., the vortex lattice moves forward by an integer number of the period of pinning array at each cycle of I rf ; and ͑4͒ very weak ratchet effect at several GHz, indicating the possibility of stronger inertia effects in the vortex motion at such high frequencies. These results reveal rich physics information in the nonadiabatic ratchet system and are of particular importance for particle separation and molecular motor in biology.

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Section: B Sudden V Dc Reversal At Large I Rfmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-frequency vortex ratchet effect in a superconducting film with a nanoengineered array of asymmetric pinning sites

et al. 2010

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“…Despite a great deal of theoretical efforts [11][12][13][14][15] aimed at the description of the ratchet dynamics of vortices in asymmetrical pinning potentials, these systems are still quite far from being completely understood. The vortex motion itself, in the presence of strong pinning sites, is still a subject of intense study.…”

Section: Introductionmentioning

confidence: 99%

Vortex ratchet effects in films with a periodic array of antidots

et al. 2006

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The vortex ratchet effect has been studied in Al films patterned with square arrays of submicron antidots. We have investigated the transport properties of two sets of samples: ͑i͒ asymmetrical antidots where vortices are driven by an unbiased ac current and ͑ii͒ symmetrical antidots where in addition to the ac drive a dc bias was used. For each sample, the rectified dc voltage is measured as a function of drive amplitude and frequency, magnetic field, and temperature. As unambiguously shown by our data, the voltage rectification in the asymmetric antidots is induced by the intrinsic asymmetry in the pinning potential created by the antidots, whereas the rectification in the symmetric antidots is induced by the dc bias. In addition, the experiments reveal interesting collective phenomena in the vortex ratchet effect. At fields below the first matching field ͑H 1 ͒, the dc-voltage-ac-drive characteristics present two rectification peaks, which is interpreted as an interplay between the one-dimensional motion of weakly pinned incommensurate vortex rows and the two-dimensional motion of the whole vortex lattice. We also discuss the different dynamical regimes controlling the motion of interstitial and trapped vortices at fields higher than H 1 and their implications for the vortex ratchet effect.

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“…When designing and operating a device capable of transverse rectification, experimenters can vary the orientation of the pinning lattice axes, the symmetry axes of the individual traps ͑if any͒, and the direction of the injected current ͑i.e., of the Lorentz force͒. Many have explored by numerical simulation the geometries best suited for the experimental implementation of this concept ͑Zhu et al, 2001;Reichhardt and Reichhardt, 2005͒. The most recent realizations of transverse fluxon rectifiers fall into two main categories.…”

Section: B Fluxon Rectification In 2d Arraysmentioning

confidence: 99%

Artificial Brownian motors: Controlling transport on the nanoscale

2009

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In systems possessing spatial or dynamical symmetry breaking, Brownian motion combined with unbiased external input signals, deterministic and random alike, can assist directed motion of particles at submicron scales. In such cases, one speaks of "Brownian motors." In this review the constructive role of Brownian motion is exemplified for various physical and technological setups, which are inspired by the cellular molecular machinery: the working principles and characteristics of stylized devices are discussed to show how fluctuations, either thermal or extrinsic, can be used to control diffusive particle transport. Recent experimental demonstrations of this concept are surveyed with particular attention to transport in artificial, i.e., nonbiological, nanopores, lithographic tracks, and optical traps, where single-particle currents were first measured. Much emphasis is given to two-and three-dimensional devices containing many interacting particles of one or more species; for this class of artificial motors, noise rectification results also from the interplay of particle Brownian motion and geometric constraints. Recently, selective control and optimization of the transport of interacting colloidal particles and magnetic vortices have been successfully achieved, thus leading to the new generation of microfluidic and superconducting devices presented here. The field has recently been enriched with impressive experimental achievements in building artificial Brownian motor devices that even operate within the quantum domain by harvesting quantum Brownian motion. Sundry akin topics include activities aimed at noise-assisted shuttling other degrees of freedom such as charge, spin, or even heat and the assembly of chemical synthetic molecular motors. This review ends with a perspective for future pathways and potential new applications.

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Vortex dynamics in regular arrays of asymmetric pinning centers

Cited by 33 publications

References 16 publications

High-frequency vortex ratchet effect in a superconducting film with a nanoengineered array of asymmetric pinning sites

High-frequency vortex ratchet effect in a superconducting film with a nanoengineered array of asymmetric pinning sites

Vortex ratchet effects in films with a periodic array of antidots

Artificial Brownian motors: Controlling transport on the nanoscale

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