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Bag B, Shaw G, Banerjee SS, Majumdar S, Sood AK, Grover AK. Negative velocity fluctuations and non-equilibrium fluctuation relation for a driven high critical current vortex state. Sci Rep 2017; 7:5531. [PMID: 28717176 PMCID: PMC5514132 DOI: 10.1038/s41598-017-05191-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/24/2017] [Indexed: 11/09/2022] Open
Abstract
Under the influence of a constant drive the moving vortex state in 2H-NbS2 superconductor exhibits a negative differential resistance (NDR) transition from a steady flow to an immobile state. This state possesses a high depinning current threshold ([Formula: see text]) with unconventional depinning characteristics. At currents well above [Formula: see text], the moving vortex state exhibits a multimodal velocity distribution which is characteristic of vortex flow instabilities in the NDR regime. However at lower currents which are just above [Formula: see text], the velocity distribution is non-Gaussian with a tail extending to significant negative velocity values. These unusual negative velocity events correspond to vortices drifting opposite to the driving force direction. We show that this distribution obeys the Gallavotti-Cohen Non-Equilibrium Fluctuation Relation (GC-NEFR). Just above [Formula: see text], we also find a high vortex density fluctuating driven state not obeying the conventional GC-NEFR. The GC-NEFR analysis provides a measure of an effective energy scale (E eff ) associated with the driven vortex state. The E eff corresponds to the average energy dissipated by the fluctuating vortex state above [Formula: see text]. We propose the high E eff value corresponds to the onset of high energy dynamic instabilities in this driven vortex state just above [Formula: see text].
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Affiliation(s)
- Biplab Bag
- Department of Physics, Indian Institute of Technology, Kanpur, 208016, India
| | - Gorky Shaw
- Department of Physics, Indian Institute of Technology, Kanpur, 208016, India
- Experimental Physics of Nanostructured Materials, Q-MAT, CESAM, Universitè de Liège, Sart Tilman, B-4000, Belgium
| | - S S Banerjee
- Department of Physics, Indian Institute of Technology, Kanpur, 208016, India.
| | - Sayantan Majumdar
- Department of Physics, Indian Institute of Science, Bengaluru, 560012, India
- James Franck Institute, The University of Chicago, Chicago, Illinois, 60637, USA
| | - A K Sood
- Department of Physics, Indian Institute of Science, Bengaluru, 560012, India.
| | - A K Grover
- Department of Physics, Panjab University, Chandigarh, 160014, India.
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Researc, Mumbai, 400005, India.
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2
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Vieira CM, Carmona HA, Andrade JS, Moreira AA. General continuum approach for dissipative systems of repulsive particles. Phys Rev E 2016; 93:060103. [PMID: 27415187 DOI: 10.1103/physreve.93.060103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Indexed: 11/07/2022]
Abstract
We propose a general coarse-graining method to derive a continuity equation that describes any dissipative system of repulsive particles interacting through short-ranged potentials. In our approach, the effect of particle-particle correlations is incorporated to the overall balance of energy, and a nonlinear diffusion equation is obtained to represent the overdamped dynamics. In particular, when the repulsive interaction potential is a short-ranged power law, our approach reveals a distinctive correspondence between particle-particle energy and the generalized thermostatistics of Tsallis for any nonpositive value of the entropic index q. Our methodology can also be applied to microscopic models of superconducting vortices and complex plasma, where particle-particle correlations are pronounced at low concentrations. The resulting continuum descriptions provide elucidating and useful insights on the microdynamical behavior of these physical systems. The consistency of our approach is demonstrated by comparison with molecular dynamics simulations.
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Affiliation(s)
- César M Vieira
- Departamento de Física, Universidade Federal do Ceará, 60451-970 Fortaleza, Brazil
| | - Humberto A Carmona
- Departamento de Física, Universidade Federal do Ceará, 60451-970 Fortaleza, Brazil
| | - José S Andrade
- Departamento de Física, Universidade Federal do Ceará, 60451-970 Fortaleza, Brazil
| | - André A Moreira
- Departamento de Física, Universidade Federal do Ceará, 60451-970 Fortaleza, Brazil
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3
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Trastoy J, Malnou M, Ulysse C, Bernard R, Bergeal N, Faini G, Lesueur J, Briatico J, Villegas JE. Freezing and thawing of artificial ice by thermal switching of geometric frustration in magnetic flux lattices. NATURE NANOTECHNOLOGY 2014; 9:710-715. [PMID: 25129072 DOI: 10.1038/nnano.2014.158] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 07/02/2014] [Indexed: 06/03/2023]
Abstract
The problem of an ensemble of repulsive particles on a potential-energy landscape is common to many physical systems and has been studied in multiple artificial playgrounds. However, the latter usually involve fixed energy landscapes, thereby impeding in situ investigations of the particles' collective response to controlled changes in the landscape geometry. Here, we experimentally realize a system in which the geometry of the potential-energy landscape can be switched using temperature as the control knob. This realization is based on a high-temperature superconductor in which we engineer a nanoscale spatial modulation of the superconducting condensate. Depending on the temperature, the flux quanta induced by an applied magnetic field see either a geometrically frustrated energy landscape that favours an ice-like flux ordering, or an unfrustrated landscape that yields a periodic flux distribution. This effect is reflected in a dramatic change in the superconductor's magneto-transport. The thermal switching of the energy landscape geometry opens new opportunities for the study of ordering and reorganization in repulsive particle manifolds.
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Affiliation(s)
- J Trastoy
- 1] Unité Mixte de Physique CNRS/Thales, 1 ave. A. Fresnel, 91767 Palaiseau, France [2] Université Paris Sud, 91405 Orsay, France
| | - M Malnou
- LPEM, ESPCI-CNRS-UPMC, 10 rue Vauquelin 75231 Paris, France
| | - C Ulysse
- CNRS, Phynano Team, Laboratoire de Photonique et de Nanostructures, route de Nozay, 91460 Marcoussis, France
| | - R Bernard
- 1] Unité Mixte de Physique CNRS/Thales, 1 ave. A. Fresnel, 91767 Palaiseau, France [2] Université Paris Sud, 91405 Orsay, France
| | - N Bergeal
- LPEM, ESPCI-CNRS-UPMC, 10 rue Vauquelin 75231 Paris, France
| | - G Faini
- CNRS, Phynano Team, Laboratoire de Photonique et de Nanostructures, route de Nozay, 91460 Marcoussis, France
| | - J Lesueur
- LPEM, ESPCI-CNRS-UPMC, 10 rue Vauquelin 75231 Paris, France
| | - J Briatico
- 1] Unité Mixte de Physique CNRS/Thales, 1 ave. A. Fresnel, 91767 Palaiseau, France [2] Université Paris Sud, 91405 Orsay, France
| | - Javier E Villegas
- 1] Unité Mixte de Physique CNRS/Thales, 1 ave. A. Fresnel, 91767 Palaiseau, France [2] Université Paris Sud, 91405 Orsay, France
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4
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McDermott D, Amelang J, Reichhardt CJO, Reichhardt C. Dynamic regimes for driven colloidal particles on a periodic substrate at commensurate and incommensurate fillings. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062301. [PMID: 24483438 DOI: 10.1103/physreve.88.062301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Indexed: 06/03/2023]
Abstract
We numerically examine colloidal particles driven over a muffin tin substrate. Previous studies of this model identified a variety of commensurate and incommensurate static phases in which topological defects can form domain walls, ordered stripes, superlattices, or disordered patchy regimes as a function of the filling fraction. Here, we show that the addition of an external drive to these static phases can produce distinct dynamical responses. At incommensurate fillings the flow occurs in the form of localized pulses or solitons correlated with topological defect structures. Transitions between different modes of motion can occur as a function of increasing drive. We measure the average particle velocity for specific ranges of external drive and show that changes in the velocity response correlate with changes in the topological defect arrangements. We also demonstrate that in the different dynamic phases, the particles have distinct trajectories and velocity distributions. Dynamic transitions between ordered and disordered flows exhibit hysteresis, while in strongly disordered regimes there is no hysteresis and the velocity-force curves are smooth. When stripe patterns are present, transport can occur at an angle to the driving direction.
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Affiliation(s)
- D McDermott
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 USA and Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 USA
| | - J Amelang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 USA and Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125 USA
| | - C J Olson Reichhardt
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 USA
| | - C Reichhardt
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 USA
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Ray D, Olson Reichhardt CJ, Jankó B, Reichhardt C. Strongly enhanced pinning of magnetic vortices in type-II superconductors by conformal crystal arrays. PHYSICAL REVIEW LETTERS 2013; 110:267001. [PMID: 23848910 DOI: 10.1103/physrevlett.110.267001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Indexed: 06/02/2023]
Abstract
Conformal crystals are nonuniform structures created by a conformal transformation of regular two-dimensional lattices. We show that gradient-driven vortices interacting with a conformal pinning array exhibit substantially stronger pinning effects over a much larger range of field than found for random or periodic pinning arrangements. The pinning enhancement is partially due to matching of the critical flux gradient with the pinning gradient, but the preservation of local ordering in the conformally transformed hexagonal lattice and the arching arrangement of the pinning also play crucial roles. Our results can be generalized to a wide class of gradient-driven interacting particle systems such as colloids on optical trap arrays.
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Affiliation(s)
- D Ray
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Rejniak KA, Estrella V, Chen T, Cohen AS, Lloyd MC, Morse DL. The role of tumor tissue architecture in treatment penetration and efficacy: an integrative study. Front Oncol 2013; 3:111. [PMID: 23717812 PMCID: PMC3650652 DOI: 10.3389/fonc.2013.00111] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/22/2013] [Indexed: 12/02/2022] Open
Abstract
Despite the great progress that has been made in understanding cancer biology and the potential molecular targets for its treatment, the majority of drugs fail in the clinical trials. This may be attributed (at least in part) to the complexity of interstitial drug transport in the patient’s body, which is hard to test experimentally. Similarly, recent advances in molecular imaging have led to the development of targeted biomarkers that can predict pharmacological responses to therapeutic interventions. However, both the drug and biomarker molecules need to access the tumor tissue and be taken up into individual cells in concentrations sufficient to exert the desired effect. To investigate the process of drug penetration at the mesoscopic level we developed a computational model of interstitial transport that incorporates the biophysical properties of the tumor tissue, including its architecture and interstitial fluid flow, as well as the properties of the agents. This model is based on the method of regularized Stokeslets to describe the fluid flow coupled with discrete diffusion-advection-reaction equations to model the dynamics of the drugs. Our results show that the tissue cellular porosity and density influence the depth of penetration in a non-linear way, with sparsely packed tissues being traveled through more slowly than the denser tissues. We demonstrate that irregularities in the cell spatial configurations result in the formation of interstitial corridors that are followed by agents leading to the emergence of tissue zones with less exposure to the drugs. We describe how the model can be integrated with in vivo experiments to test the extravasation and penetration of the targeted biomarkers through the tumor tissue. A better understanding of tissue- or compound-specific factors that limit the penetration through the tumors is important for non-invasive diagnoses, chemotherapy, the monitoring of treatment responses, and the detection of tumor recurrence.
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Affiliation(s)
- Katarzyna A Rejniak
- Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center and Research Institute Tampa, FL, USA ; Department of Oncologic Sciences, College of Medicine, University of South Florida Tampa, FL, USA
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7
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Libál A, Reichhardt C, Reichhardt CJO. Point-defect dynamics in two-dimensional colloidal crystals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:011403. [PMID: 17358146 DOI: 10.1103/physreve.75.011403] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Indexed: 05/14/2023]
Abstract
We study the topological configurations and dynamics of individual point defect vacancies and interstitials in a two-dimensional crystal of colloids interacting via a repulsive Yukawa potential. Our Brownian dynamics simulations show that the diffusion mechanism for vacancy defects occurs in two phases. The defect can glide along the crystal lattice directions, and it can rotate during an excited topological transition configuration to assume a different direction for the next period of gliding. The results for the vacancy defects are in good agreement with recent experiments. For interstitial point defects, which were not studied in the experiments, we find several of the same modes of motion as in the vacancy defect case along with two additional diffusion pathways. The interstitial defects are more mobile than the vacancy defects due to the more two-dimensional nature of the diffusion of the interstitial defects.
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Affiliation(s)
- A Libál
- Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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8
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Berdiyorov GR, Milosević MV, Peeters FM. Novel commensurability effects in superconducting films with antidot arrays. PHYSICAL REVIEW LETTERS 2006; 96:207001. [PMID: 16803196 DOI: 10.1103/physrevlett.96.207001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Indexed: 05/10/2023]
Abstract
Vortex configurations in superconducting films with regular arrays of antidots (holes) are calculated within the nonlinear Ginzburg-Landau theory. In addition to the well-established matching phenomena, we predict (i) the nucleation of giant-vortex states between the antidots, (ii) the combination of giant- and multivortices at rational matching fields, and (iii) for particular values of the vorticity, symmetry imposed creation of vortex-antivortex configurations.
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Affiliation(s)
- G R Berdiyorov
- Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
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9
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Zhu BY, Marchesoni F, Nori F. Controlling the motion of magnetic flux quanta. PHYSICAL REVIEW LETTERS 2004; 92:180602. [PMID: 15169477 DOI: 10.1103/physrevlett.92.180602] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2003] [Indexed: 05/24/2023]
Abstract
We study the transport of vortices in superconductors with triangular arrays of boomerang- or V-shaped asymmetric pinning wells, when applying an alternating electrical current. The asymmetry of the pinning landscape induces a very efficient "diode" effect, that allows the sculpting at will of the magnetic field profile inside the sample. We present the first quantitative study of magnetic "lensing" of fluxons inside superconductors. Our proposed vortex lens provides a near threefold increase of the vortex density at its "focus" regions. The main numerical features have been derived analytically.
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Affiliation(s)
- B Y Zhu
- Frontier Research System, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351-0198, Japan
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10
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Grigorenko AN, Bending SJ, Van Bael MJ, Lange M, Moshchalkov VV, Fangohr H, de Groot PAJ. Symmetry locking and commensurate vortex domain formation in periodic pinning arrays. PHYSICAL REVIEW LETTERS 2003; 90:237001. [PMID: 12857280 DOI: 10.1103/physrevlett.90.237001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2002] [Indexed: 05/24/2023]
Abstract
The spontaneous formation of domains of commensurate vortex patterns near rational fractional matching fields of a periodic pinning array has been investigated with high resolution scanning Hall probe microscopy. We show that domain formation is promoted due to the efficient incorporation of mismatched excess vortices and vacancies at the corners of domain walls, which outweighs the energetic cost of creating them. Molecular dynamics simulations with a generic pinning potential reveal that domains are formed only when vortex-vortex interactions are long range.
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Affiliation(s)
- A N Grigorenko
- Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
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11
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Field SB, James SS, Barentine J, Metlushko V, Crabtree G, Shtrikman H, Ilic B, Brueck SRJ. Vortex configurations, matching, and domain structure in large arrays of artificial pinning centers. PHYSICAL REVIEW LETTERS 2002; 88:067003. [PMID: 11863844 DOI: 10.1103/physrevlett.88.067003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2000] [Indexed: 05/23/2023]
Abstract
High-resolution scanning Hall probe microscopy has been used to image vortex configurations in very large periodic arrays of artificial pinning sites. Strong matching effects are seen at fields where either one or two vortices can sit at a site; with three vortices per site, however, no clear matching is observed. Matching effects have also been observed at several fractional multiples of the matching field, including 1/5, 1/4, 1/3, 1/2, and 3/4. These fractional values are characterized by striking domain structure and grain boundaries.
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Affiliation(s)
- S B Field
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
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12
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Zapperi S, Moreira AA, Andrade JS. Flux front penetration in disordered superconductors. PHYSICAL REVIEW LETTERS 2001; 86:3622-3625. [PMID: 11328038 DOI: 10.1103/physrevlett.86.3622] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2000] [Indexed: 05/23/2023]
Abstract
We investigate flux front penetration in a disordered type-II superconductor by molecular dynamics simulations of interacting vortices and find scaling laws for the front position and the density profile. The scaling can be understood by performing a coarse graining of the system and writing a disordered nonlinear diffusion equation. Integrating numerically the equation, we observe a crossover from flat to fractal front penetration as the system parameters are varied. The value of the fractal dimension indicates that the invasion process is described by gradient percolation.
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Affiliation(s)
- S Zapperi
- INFM sezione di Roma 1, Dipartimento di Fisica, Università La Sapienza, P.le A. Moro 2, 00185 Roma, Italy
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13
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Observation of plastic flows of vortices in superconductors at the depinning threshold by Lorentz microscopy. Micron 1999. [DOI: 10.1016/s0968-4328(99)00048-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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