The dynamics of the Bean critical state

Barford, William; Beere, W.H.; Steer, M. J.

doi:10.1088/0953-8984/5/27/002

Cited by 12 publications

(6 citation statements)

References 6 publications

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“…Care must be taken, however, since the results can be sensitive to the selected set of rules (see, for example, Kadanoff et al, 1989). After the pioneering application of molecular dynamics techniques in the investigation of vortex avalanches in the critical state by Richardson et al (1994), extensive work on the subject was generated (Barford et al, 1993;Plá et al, 1996;Olson, Reichhardt, Groth, Field, and Nori, 1997;. A molecular dynamics simulation of a slowly driven critical state can be illustrated by the approach of : For every vortex, i, they solve the overdamped equation of motion…”

Section: B Dynamically and Thermally Driven Avalanchesmentioning

confidence: 99%

Colloquium: Experiments in vortex avalanches

2004

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Avalanche dynamics are found in many phenomena, from earthquakes to the evolution of species. They can also be found in vortex matter when a type-II superconductor is externally driven, for example, by an increasing magnetic field. Vortex avalanches associated with thermal instabilities can be an undesirable effect for applications, but ''dynamically driven'' avalanches emerging from the competition between intervortex interactions and quenched disorder may provide an interesting test scenario for nonequilibrium dynamics theory. In contrast to the equilibrium phases of vortex matter in type-II superconductors, the corresponding dynamical phases-in which avalanches can play a role-are only beginning to be studied. This article reviews relevant experiments performed in the last decade or so, emphasizing the ability of different experimental techniques to establish the nature and statistical properties of avalanche behavior. CONTENTS

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Section: B Dynamically and Thermally Driven Avalanchesmentioning

confidence: 99%

Colloquium: Experiments in vortex avalanches

2004

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“…For instance, type-II superconductors can be populated by vortices of super-currents that pierce the system in the direction of the applied magnetic field [1]. These vortices can be considered as single particles, and will dissipate energy as long as they move [2][3][4][5][6]. Another notable example is complex plasma [7,8], where charged microparticles are immersed in an ionized gas.…”

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confidence: 99%

General continuum approach for dissipative systems of repulsive particles

et al. 2016

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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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“…If a robust parameterisation of oligophenylenes can be achieved, by which we mean a reasonably accurate prediction of exciton energies, then other quantities, such as oscillator strengths, non-linear optical coefficients and correlation functions can be calculated with some confidence. This is the subject of [31].…”

Section: Discussionmentioning

confidence: 98%

“…The accuracy is even better in the interacting case where states are more localised and gaps are widened [32]. A systematic analysis of the convergence of energies in (8) is presented elsewhere [31]. Table 5 shows the energies of the vertical transitions as a function of oligomer length of the 1 3 B + 1u , the 1 1 B − 1u and the lowest even, covalent excitation, which we label as m 1 A + g .…”

Section: Oligophenylenes: the Wannier 2-mo Modelmentioning

confidence: 99%

Molecular orbital models of benzene, biphenyl and the oligophenylenes

1999

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A two state (2-MO) model for the low-lying long axis-polarised excitations of poly(p-phenylene) oligomers and polymers is developed. First we derive such a model from the underlying Pariser-Parr-Pople (P-P-P) model of π-conjugated systems. The two states retained per unit cell are the Wannier functions associated with the valence and conduction bands. By a comparison of the predictions of this model to a four state model (which includes the non-bonding states) and a full P-P-P model calculation on benzene and biphenyl, it is shown quantitatively how the 2-MO model fails to predict the correct excitation energies. The 2-MO model is then solved for oligophenylenes of up to 15 repeat units using the density matrix renormalisation group (DMRG) method. It is shown that the predicted lowest lying, dipole allowed excitation is ca. 1 eV higher than the experimental result. The failure of the 2-MO model is a consequence of the fact that the original HOMO and LUMO single particle basis does not provide an adequate representation for the many body processes of the electronic system.

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The dynamics of the Bean critical state

Cited by 12 publications

References 6 publications

Colloquium: Experiments in vortex avalanches

Colloquium: Experiments in vortex avalanches

General continuum approach for dissipative systems of repulsive particles

Molecular orbital models of benzene, biphenyl and the oligophenylenes

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