Insulator-Superconductor Transition in 3D Granular Al-Ge Films

Gerber, A.; Milner, A.; Deutscher, G.; Karpovsky, Mark G.; Gladkikh, A.

doi:10.1103/physrevlett.78.4277

Cited by 175 publications

(206 citation statements)

References 33 publications

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“…(4)- (8) with experimental data may serve as a good check of the theory developed here. The logarithmic dependence ρ xx = a + b ln T of granular metals has been observed experimentally [8], and ρ xy can also be measured [9]. Our theory may also be applied to indium tin oxide(ITO) materials (see e.g.…”

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confidence: 62%

Hall Resistivity of Granular Metals

Kharitonov

Efetov

2007

Phys. Rev. Lett.

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We calculate the Hall conductivity σxy and resistivity ρxy of a granular system at large tunneling conductance gT ≫ 1. We show that in the absence of Coulomb interaction the Hall resistivity depends neither on the tunneling conductance nor on the intragrain disorder and is given by the classical formula ρxy = H/(n * ec), where n * differs from the carrier density n inside the grains by a numerical coefficient determined by the shape of the grains. The Coulomb interaction gives rise to logarithmic in temperature T correction to ρxy in the range Γ T min(gT Ec, E Th ), where Γ is the tunneling escape rate, Ec is the charging energy and E Th is the Thouless energy of the grain. does not depend on the mean free path and allows one to experimentally determine the carrier concentration n. Recently, much attention from both experimental and theoretical sides has been paid to granular systems (see a review [1] and references therein). Although various physical quantities have been calculated in different regimes, the Hall transport in the granular matter has not been addressed theoretically yet. In this work we calculate the Hall conductivity(HC) of a granular system and Coulomb interaction corrections to it in the metallic regime, when the intergrain tunneling conductance G T = (2e 2 / )g T is large, g T ≫ 1 (further we set = 1).Technically, calculating HC σ xy appears to be more complicated than calculating the longitudinal conductivity(LC) σ xx . The granularity of the system is ensured by the condition that the conductance G 0 = 2e 2 g 0 of the grain is much larger than the tunneling conductance G T , g 0 /g T ≫ 1. In this limit the main contribution to σ xx comes from the tunnel barriers between the grains rather than from scattering on impurities inside the grains. In the absence of Coulomb interaction LC equalswhere a is the size of the grains and d is the dimensionality of the system. Therefore when studying longitudinal transport one can neglect electron dynamics inside the grains, which simplifies calculations significantly. On the contrary, for Hall transport one is forced to take the intragrain electron dynamics into account, since the Hall current originates from the transversal drift in crossed magnetic and electric fields inside the grains. As we find in this work the intragrain electron dynamics can be included within the diagrammatic approach by considering higher diffusion modes inside the grain. This procedures accounts for the finiteness of the ratio g T /g 0 , and allows one, in principle, to study both LC and HC of the granular system for arbitrary ratio g T /g 0 . The obtained results reproduce the solution of the classical electrodynamics problem for a granular medium (e.g. the formulacan be obtained as a series in g T /g 0 ). Quantum effects (e.g. Coulomb interaction and weak localization) may be incorporated into this scheme afterwards.We perform calculations for magnetic fields H such that ω H τ ≪ 1, where ω H = eH/mc is the Larmor frequency and τ is the electron scattering time inside the grai...

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mentioning

confidence: 62%

Hall Resistivity of Granular Metals

Kharitonov

Efetov

2007

Phys. Rev. Lett.

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“…Several explanations have been advanced for this striking behavior, but real understanding was achieved only recently (Beloborodov et al, 2005c;Feigel'man and Ioselevich, 2005;Tran et al, 2005;Zhang and Shklovskii, 2004). A most recent incitement to intense and deep study of physics of granular materials was given by the influential works (Gerber et al, 1997;Simon et al, 1987) where a logarithmic dependence of the conductivity σ (T ) σ (T ) = a + b ln T ,…”

Section: Introductionmentioning

confidence: 99%

“…Superconductivity brings yet another aspect to diversity of the interesting effects in granular materials (Gerber et al, 1997;Hadacek et al, 2004;Jaeger et al, 1989;Shapira and Deutscher, 1983). One of them is a counterintuitive suppression of the conductivity due to superconducting fluctuations.…”

Section: Introductionmentioning

confidence: 99%

Granular electronic systems

et al. 2007

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A granular metal is an array of metallic nano-particles imbedded into an insulating matrix. Tuning the intergranular coupling strength a granular system can be transformed into either a good metal or an insulator and, in case of superconducting particles, experience superconductor-insulator transition. The ease of adjusting electronic properties of granular metals makes them most suitable for fundamental studies of disordered solids and assures them a fundamental role for nanotechnological applications. This Review discusses recent important theoretical advances in the study of granular metals, emphasizing on the interplay of disorder, quantum effects, fluctuations and effects of confinement in formation of electronic transport and thermodynamic properties of granular materials.

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“…The electronic transport properties of granular metals are governed by the (inelastic) tunneling between metallic grains through the potential associated with the dielectric matrix. In accordance with the strength of the intergrain tunneling granular metals show either non-insulating or insulating behavior [4,5]. For mid intergrain coupling, due to the ability of fine tuning, granular metals are considered to be ideal model systems to study the metal-insulator transition (MIT) [3,6,7].…”

Section: Introductionmentioning

confidence: 99%

Tuning the electrical conductivity of Pt-containing granular metals by postgrowth electron irradiation

Porrati

Sachser

Schwalb

et al. 2011

Journal of Applied Physics

103

171

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We have fabricated Pt-containing granular metals by focused electron beam induced deposition from the (CH3)3CH3C5H4Pt precursor gas. The granular metals are made of platinum nanocrystallites embedded in a carbonaceous matrix. We have exposed the asgrown nanocomposites to low energy electron beam irradiation and we have measured the Finally, by means of AFM measurements we observe a reduction of the volume of the samples with increasing irradiation time which we attribute to the removal of carbon molecules.

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Insulator-Superconductor Transition in 3D Granular Al-Ge Films

Cited by 175 publications

References 33 publications

Hall Resistivity of Granular Metals

Hall Resistivity of Granular Metals

Granular electronic systems

Tuning the electrical conductivity of Pt-containing granular metals by postgrowth electron irradiation

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