Evidence for two-dimentional quantum Wigner crystal

Goldman, V. J.; Santos, M. B.; Shayegan, M.; Cunningham, J. E.

doi:10.1103/physrevlett.65.2189

Cited by 366 publications

(290 citation statements)

References 16 publications

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“…Our findings strongly support these previous theoretical works and we believe it will reopen the enthusiasm to study experimentally in more detail the different properties of the dynamic vortex phases. Moreover, in exploding the analogies of a vortex lattice in a periodic pinning potential with other elastic systems, the present findings can be relevant for the research on dynamic phases in Wigner crystals 17,18 and colloidal molecular crystals pinned by an array of optical traps. 19,20 …”

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Transition from turbulent to nearly laminar vortex flow in superconductors with periodic pinning

et al. 2009

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We revisit the vortex dynamics in Al thin films containing an artificial periodic array of antidots by means of electrical transport measurements. We clearly identify a turbulent to laminarlike vortex flow transition which manifests itself as a negative differential resistivity. This transition is accompanied by a strong irreversibility in the voltage-current characteristics. The dynamical phase diagrams obtained as a function of commensurability, temperature, and driving force are in good agreement with the early predictions by Reichhardt et al. ͓Phys. Rev. Lett. 78, 2648 ͑1997͔͒ based on molecular dynamic simulations. DOI: 10.1103/PhysRevB.80.140514 PACS number͑s͒: 74.25.Qt, 74.25.Dw, 74.40.ϩk, 74.78.Na The pioneering work of Giaever 1 provided the first experimental evidence that dc electrical resistance in type-II superconductors is a direct consequence of the motion of Abrikosov vortices.Extensive molecular dynamics ͑MD͒ simulations of array of vortices treated as overdamped objects interacting repulsively with each other and moving over a predefined potential landscape have proven to be a remarkably successful tool to describe the vortex dynamics in all sort of superconductors. 2 Superconductors with a periodic array of pinning centers represent a unique playground to investigate the interaction between vortices and pinning sites. [3][4][5] Early MD simulations for this particular system by Reichhardt et al. 6,7 predicted a remarkable property, namely, the existence of a dynamic transition from a highly dissipative disordered vortex flow at low driving forces to a less dissipative state of ordered flow where pinned vortices coexist with fast solitonlike excitations at higher currents. The sequence in which these dynamical phases appear is highly nontrivial and even counterintuitive since it implies a reduction of the average vortex mobility by increasing the driving force.In spite of the great deal of attention that this fascinating discovery has received in the superconducting community, so far there has been no experimental confirmation of it. A possible cause, recently pointed out by Misko et al.,8,9 is that strong heating or disorder effects can mask this effect. In this Rapid Communication we provide unambiguous experimental evidence that a superconducting film with a periodic array of antidots exhibits a clear turbulent to laminarlike vortex flow transition provided that heat removal is efficient. This transition appears as a negative differential resistivity in the current-voltage characteristics. We demonstrate that the loci of the dynamic transitions in a magnetic field-temperature phase diagram are highly sensitive to the pinning strength and commensurability of the system. At high bias currents the simplified model of a vortex as a pointlike classical particle which ignores the internal structure of the vortex and its elastic nature seems to fail and more realistic approaches, such as time dependent Ginzburg-Landau formalism, become necessary.The investigated sample consists of an Al film of...

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Transition from turbulent to nearly laminar vortex flow in superconductors with periodic pinning

et al. 2009

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“…We recall two such examples here: the first is in one-dimensional or-ganic and inorganic solids where thresholds to conduction have been treated as the signature of the depinning of charge density waves [19]. Similarly, in 2D electron systems confined in semiconductor heterostructures, thresholds for conduction have been attributed to the depinning of a magnetically induced electron solid akin to the Wigner crystal [20,21,22].…”

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Experimental Evidence for a Collective Insulating State in Two-Dimensional Superconductors

et al. 2005

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We present the results of an experimental study of the current-voltage characteristics in strong magnetic field (B) of disordered, superconducting, thin-films of amorphous Indium-Oxide. As the B strength is increased superconductivity degrades, until a critical field (B c ) where the system is forced into an insulating state. We show that the differential conductance measured in the insulating phase vanishes abruptly below a well-defined temperature, resulting in a clear threshold for conduction. Our results indicate that a new collective state emerges in two-dimensional superconductors at high B.

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“…In low-disorder 2D systems, a sufficiently large B is expected to quench the kinetic energy of the carriers, leading to the formation of a Wigner solid (WS) [2]. Experimental evidence has been accumulated for the existence of a WS in both GaAs 2D electron singlelayers [1,2,3,4] around the fractional quantum Hall state at Landau level filling factor ν = 1 5 and electron bilayers [5] in the vicinity of total filling factor ν = 1 2 , as well as in dilute, single-layer, GaAs 2D hole systems [6] near ν = 1 3 . Recently, a reentrant insulating phase (IP) was observed in interacting GaAs bilayer hole systems around the many-body quantum Hall state (QHS) at total filling factor ν = 1 [7].…”

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Thermopower of Interacting GaAs Bilayer Hole Systems in the Reentrant Insulating Phase Nearν=1

et al. 2005

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We report thermopower measurements of interacting GaAs bilayer hole systems. When the carrier densities in the two layers are equal, these systems exhibit a reentrant insulating phase near the quantum Hall state at total filling factor ν = 1. Our data show that as the temperature is decreased, the thermopower diverges in the insulating phase. This behavior indicates the opening of an energy gap at low temperature, consistent with the formation of a pinned Wigner solid. We extract an energy gap and a Wigner solid melting phase diagram.

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Evidence for two-dimentional quantum Wigner crystal

Cited by 366 publications

References 16 publications

Transition from turbulent to nearly laminar vortex flow in superconductors with periodic pinning

Transition from turbulent to nearly laminar vortex flow in superconductors with periodic pinning

Experimental Evidence for a Collective Insulating State in Two-Dimensional Superconductors

Thermopower of Interacting GaAs Bilayer Hole Systems in the Reentrant Insulating Phase Nearν=1

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