Conductance fluctuations in a ballistic metallic point contact

Holweg, P.A.M.; Kokkedee, J.A.; Caro, J.; Verbruggen, A. H.; Radelaar, S.; Jansen, A. G. M.; Wyder, P.

doi:10.1103/physrevlett.67.2549

Cited by 70 publications

(46 citation statements)

References 20 publications

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“…That these are characteristic of strongly disordered constrictions and can be interpreted as universal conductance fluctuations due to quantum interference, was established in a separate investigation [36], [11, chapter 4], [37].…”

Section: Experimental Facts For Quenched Cu Samplesmentioning

confidence: 99%

The 2-Channel Kondo Model

et al. 1998

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Certain zero-bias anomalies (ZBAs) in the voltage, temperature and magnetic field dependence of the conductance G(V, T, H) of quenched Cu point contacts have previously been interpreted to be due to non-magnetic 2-channel Kondo (2CK) scattering from near-degenerate atomic two-level tunneling systems (Ralph and Buhrman, 1992;, and hence to represent an experimental realization of the non-Fermi-liquid physics of the T = 0 fixed point of the 2-channel Kondo model. In this, the first in a series of three papers (I,II,III) devoted to 2-channel Kondo physics, we present a comprehensive review of the quenched Cu ZBA experiments and their 2CK interpretation, including new results on ZBAs in constrictions made from Ti or from metallic glasses. We first review the evidence that the ZBAs are due to electron scattering from stuctural defects that are not static, but possess internal dynamics. In order to distinguish between several mechanisms proposed to explain the experiments, we then analyze the scaling properties of the conductance at low temperature and voltage and extract from the data a universal scaling function Γ(v). The theoretical calculation of the corresponding scaling function within the 2CK model is the subject of papers II and III. The main conclusion of our work is that the properties of the ZBAs, and most notably their scaling behavior, are in good agreement with the 2CK model and clearly different from several other proposed mechanisms.

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Section: Experimental Facts For Quenched Cu Samplesmentioning

confidence: 99%

The 2-Channel Kondo Model

et al. 1998

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“…͑2a͔͒, ␦R s is expected to vary ϰT Ϫ0.6Ϯ0. 15 . The temperature dependence of ␦R s in short wires LϽl and ␦R a ͓Eqs.…”

Section: ͑3͒mentioning

confidence: 99%

“…These experiments have been described elsewhere and we restrict ourselves here to a summary of the results. 26 We deduced an elastic mean free path l e ϭ0.8Ϯ0.1 m, a carrier density n s ϭ7.2ϫ10 15 . At temperatures Tу1.8 K the background resistance is obtained by smoothing the measured data.…”

Section: A Transport Parametersmentioning

confidence: 99%

“…This was demonstrated, for instance, by experiments of Skocpol et al, 3 Benoit et al, 4 and Haucke et al 5 on Si metal-oxide-semiconductor field-effect transistors and metal films and by theoretical work of Büttiker, 6 Hershfield, and Ambegaokar, 7 Baranger, Stone, and DiVincenzo, 8 and Chandrasekhar, Santhanam, and Prober. 9 Not only experimental work on various small structures involving the high-mobility two-dimensional electron gas in AlGaAs/GaAs heterostructures ͑e.g., narrow etched 10,11 or split-gate wires 12,13 and ballistic cavities͒ 14 but also work on three-dimensional metallic point contacts 15 shows that the condition of strict diffusive transport is not a necessary condition for the observation of conductance fluctuations. However it is not clear to what extent the theory developed for the pure diffusive transport regime is capable of describing in detail conductance fluctuations in, for instance, the quasiballistic transport regime.…”

Section: Introductionmentioning

confidence: 99%

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Magnetoresistance fluctuations in shortn-type Si/SiGe heterostructure wires

Veen¹,

Verbruggen

Drift

et al. 2000

Phys. Rev. B

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Magnetoresistance fluctuations in short quasiballistic Si/SiGe wire segments have been investigated as a function of magnetic field and temperature. The segments are measured in a four-probe geometry and the voltage probe distances L are taken smaller or larger than the phase coherence length l ͑Ϸ1.5 m at T ϭ0.1 K͒ and the electron mean free path l e ͑Ϸ0.8 m͒. At magnetic fields smaller than Bϭ1 T, the amplitude ␦R and the correlation field B c of both the symmetric and antisymmetric part of the resistance fluctuations have been studied as a function of probe distance and temperature. It is found that, despite the quasiballistic character of electron transport in our samples, the behavior of the amplitude and correlation field with probe separation is in good qualitative agreement with expressions derived for the diffusive regime. The observed magnitude of B c , however, is much larger than expected for the diffusive transport regime. A better agreement for B c is obtained using an expression adapted for the quasiballistic regime. The temperature dependence of the correlation field cannot be explained by expressions appropriate for the diffusive or the quasiballistic transport regime.

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“…In ballistic metallic microconstrictions it manifests itself as fluctuations in conductance when a magnetic field 11 or an electrical voltage is applied 12 . Now experimental efforts have been done using MCB techniques, in order to measure conductance as a function of voltage in atomic-size point contacts 1 .…”

Section: Introductionmentioning

confidence: 99%

Effect of quantum interference in the nonlinear conductance of metallic microconstrictions

2000

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The influence of the interference of electron waves, which were scattered by single impurities, on nonlinear quantum conductance of metallic microconstrictions (as was recently investigated experimentally 1,2 ) is studied theoretically. The dependence of the interference pattern in the conductance G (V ) on the contact diameter and the spatial distribution of impurities is analyzed. It is shown that the amplitude of conductance oscillation is strongly depended on the position of impurities inside the constriction.

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Conductance fluctuations in a ballistic metallic point contact

Cited by 70 publications

References 20 publications

The 2-Channel Kondo Model

The 2-Channel Kondo Model

Magnetoresistance fluctuations in shortn-type Si/SiGe heterostructure wires

Effect of quantum interference in the nonlinear conductance of metallic microconstrictions

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