Vortex-Array Model for Charge-Density-Wave Conduction Noise

Ong, Nai Phuan; Verma, G.; Maki, Kazumi

doi:10.1103/physrevlett.52.663

Cited by 215 publications

(56 citation statements)

References 18 publications

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“…We believe that this is unlikely, for the following reasons. If no additional phase slip centers [27] are introduced between the voltage leads, then the changes in E T would be apparent at any value of J x , and no J c would be observed. If there are additional phase slip centers, then a nonzero J c may be possible as a consequence of the phase slip voltage V ps needed to depin a small segment of the sample [28].…”

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confidence: 99%

Tunable Charge-Density Wave Transport in a Current-Effect Transistor

2000

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The collective charge-density wave (CDW) conduction is modulated by a transverse single-particle current in a transistorlike device. Nonequilibrium conditions in this geometry lead to an exponential reduction of the depinning threshold, allowing the CDWs to slide at much lower bias fields. The results are in excellent agreement with a recently proposed dynamical model in which "wrinkles" in the CDW wave fronts are "ironed" by the transverse current. The experiment might have important implications for other driven periodic media, such as moving vortex lattices or "striped phases" in high-T c superconductors. PACS numbers: 71.45.Lr, 72.15.Nj The charge-density wave (CDW) state, characterized by a periodic modulation of the conduction electron density, is commonly observed in low-dimensional conductors [1]. It is found to be the ground state in various inorganic and organic materials with a chainlike structure, giving rise to remarkable electrical properties [2][3][4]. Similar chargeordered states ("striped phases") play an important role in high-T c superconductors [5] and two-dimensional electron gases in the quantum Hall regime [6].A particularly interesting feature of the CDW state is its collective transport mode, very similar to superconductivity [7]: under an applied electric field, the CDWs slide along the crystal, giving rise to a strongly nonlinear conductivity. Since even a small amount of disorder pins the CDWs, sliding occurs only when the applied electric field exceeds a certain threshold field. The pinning mechanisms, the onset of collective motion, and the dynamics of a moving CDW are typical characteristics of the complex physics which describes a very general class of disordered periodic media [8][9][10][11][12][13][14][15]. These include a wide variety of periodic systems, as diverse as vortex lattices in superconductors and Josephson junction arrays [16][17][18][19], Wigner crystals [20], colloids [21], magnetic bubble arrays [22], and models of mechanical friction [23].The focus of recent theoretical and experimental research on disordered periodic media has been their nonequilibrium dynamical properties. In particular, it has been predicted that moving elastic structures still experience "transverse pinning" when motion occurs transverse to the periodicity of the structure [12], which was supported by numerical simulations [24]. In the context of CDW, one of the issues that has been raised is the effect of a single-particle current, due to uncondensed electrons and quasiparticle excitations. In a recent theoretical work, Radzihovsky and Toner [25] discovered that a singleparticle current has the most profound effects when it flows perpendicular to the CDW sliding direction. Based on general symmetry principles, this leads to nonequilibrium CDW dynamics even if CDW itself is stationary. Here we report our study of the CDW transport in the presence of such a transverse single-particle current.We find that the sliding CDW motion is stable against a small transverse current, but large currents...

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confidence: 99%

Tunable Charge-Density Wave Transport in a Current-Effect Transistor

2000

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“…It is also of theoretical interest to know if, when analyzing disordered systems, boundaries effects are of first importance or if they can be neglected compared to the pure bulk treatment of the problem. A similar question has lead to the proposition that bulk impurities play no major role in the broad band noise generation of charge density waves [7]. As a model system, the case of superconducting vortex lattices can be particularly instructing.…”

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confidence: 99%

Voltage noise and surface current fluctuations in the superconducting surface sheath

Scola¹,

Pautrat²,

Goupil³

et al. 2005

Phys. Rev. B

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We report the first measurements of the voltage noise in the surface superconductivity state of a type-II superconductor. We present strong evidences that surface vortices generates surface current fluctuations whose magnitude can be modified by the pinning ability of the surface. Simple twostage mechanism governed by current conservation appears to describe the data. We conclude that large voltage fluctuations induced by surface vortices exist while the bulk is metallic. Furthermore, this experiment shows that sole surface current fluctuations can account for the noise observed even in the presence of vortices in the bulk.PACS numbers: 74.40.+k, 74.25.Op, 72.70.+m, 74.70.Ad Separating bulk and surface effects is an ubiquitous problem in condensed matter physics. For example, Flicker noise in semi-conductors [1] and 1/f like-noise in metals [2,3] can occur from either bulk or surface localized sources. Similarly, one can cite the long standing debate about surface versus bulk effects in driven nonlinear systems like charge density waves [4] or vortex lattice in superconductors [5,6]. Such debate extends to the origin of the fluctuations responsible for their electronic noise. In any case, the key question is how to determine the relevant sources of disorder. From a technological point of view, noise is a limiting factor for most of applications, and it is necessary to know its origin before expecting its minimization. It is also of theoretical interest to know if, when analyzing disordered systems, boundaries effects are of first importance or if they can be neglected compared to the pure bulk treatment of the problem. A similar question has lead to the proposition that bulk impurities play no major role in the broad band noise generation of charge density waves [7]. As a model system, the case of superconducting vortex lattices can be particularly instructing.The dynamics of a bulk vortex lattice has been heavily studied in the literature. It is both understood and experimentally shown that the vortices, when submitted to an overcritical current I > I c and under steady state conditions, move in the bulk of the sample with a well defined average periodicity [8]. This motion is associated with a resistance R f f ≤ R n and an electrostatic field E = −V L ∧ ω (V L is the line velocity and ω the vortex field) [9]. Experimentally, it was also shown that E can be separated into its mean E and its fluctuating part δE * [10]. The latter is the electric field noise. Combined with the V-I relation V = R f f (I − I c ), one can easily realize that this noise can be expressed as fluctuations in the bulk current (I − I c ), or as fluctuations in the resistance R f f . Most of the theories invoke bulk pinning centers through their interaction with the moving vortices, leading to vortex density fluctuations and to their associated δR * f f fluctuations [10]. Alternatively, noise may arise from over-critical current fluctuations δ(I − I c ) * , while R f f is constant [12]. For the simple reason of current conservation, δ(I...

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“…Other mechanisms of the narrow band noise have also been proposed by Portis [185] and Barnes and Zawadowski [204]. We also note that Ong et al [205,206] have recenrly claimed that the noise phenomena are not a bulk effect, but they are observed only in the inhomogeneous region in a sampie ne ar the contact to leads.…”

Section: Noise Associated With the Non-ohmic Conductivitymentioning

confidence: 76%