Two-Dimensional Electrical Conductivity in Quench-Condensed Metal Films

Dynes, R. C.; Garno, J. P.; Rowell, J. M.

doi:10.1103/physrevlett.40.479

Cited by 214 publications

(110 citation statements)

References 11 publications

Supporting

Mentioning

104

Contrasting

Order By: Relevance

“…This linear behavior reflects homogeneous rather than granular film growth, which would appear as an exponential dependence. 22 Consistently, the slope, dG(8K) dd dep , is smaller and the intercept, d Gc , is larger for the NHC films compared to reference films. T 0 decreases continuously on approaching the IST (also shown in Refs.…”

supporting

confidence: 59%

Cooper-pair insulator phase in superconducting amorphous Bi films induced by nanometer-scale thickness variations

et al. 2011

View full text Add to dashboard Cite

supporting

confidence: 59%

Cooper-pair insulator phase in superconducting amorphous Bi films induced by nanometer-scale thickness variations

et al. 2011

View full text Add to dashboard Cite

“…sequential evaporation on a cryogenically cold substrate under UHV conditions, has proven to be a very useful tool for studying the SIT [7][8][9][10]. Depending on the choice of substrate, this technique enables one to probe both mechanisms of the SIT: If the samples are quench condensed on a passivated substrate (such as SiO), they grow in a granular manner so that the film brakes up into separated islands.…”

mentioning

confidence: 99%

The superconductor insulator transition in systems of ultrasmall grains

Frydman¹

2003

Physica C: Superconductivity

View full text Add to dashboard Cite

We present transport measurements on quench condensed granular Pb films in which the grains are 40 − 80Å in diameter. These films show a cross over from an insulator to a superconductor behavior as the nominal thickness of the layer is increased. This transition is different in nature than those seen in quench condensed systems reported in the past where the films were either uniform or granular with grain sizes on the order of 200Å. We discuss possible physical mechanisms for these transitions. PACS: 74.80.Bj, 74.76.Db, 74.50.+r The superconductor insulator transition (SIT) in thin layers has attracted a lot of interest for close to three decades and has been lately revived due to the possibility that it is a quantum phase transition at T=0 [1][2][3][4][5][6]. A number of theoretical scenarios have been suggested to try to explain why superconductivity is destroyed as the thickness of the layer is decreased. These can be classified into two major classes. The first invokes a "Bosonic" picture in which isolated superconducting islands exist in a non superconducting matrix [4]. Here, Cooper pairs are localized on the islands resulting in an insulating behavior of the film. The other scenario [5] proposes localization of single electrons as a result of disorder and Coulomb interaction effects.The technique of quench condensation, i.e. sequential evaporation on a cryogenically cold substrate under UHV conditions, has proven to be a very useful tool for studying the SIT [7][8][9][10]. Depending on the choice of substrate, this technique enables one to probe both mechanisms of the SIT: If the samples are quench condensed on a passivated substrate (such as SiO), they grow in a granular manner so that the film brakes up into separated islands. The average distance between the islands decreases upon adding material. In these samples there is a critical thickness d c , below which no conductivity can be measured. For granular Pb, d c ≈ 100Å. Once the thickness, d, of the sample is larger than d c , the sheet resistance, R, drops exponentially with thickness until, for R ≤ 6kΩ, it switches to a normal Ohmic behavior (R ∝ 1/d). STM measurements on quench condensed Pb granular films close to d c [11][12][13] show that the grains are about 200Å in diameter and 50-80Å in height. On the other hand when the substrate is pre-coated by a thin layer of amorphous Ge (which is insulating at 4K), the sample grows uniformly and is continuous at a thickness of 1-2 monolayers of material [7] after which the sample obeys the usual R ∝ 1/d dependence. It is believed that the large number of dangling bonds in the Ge layer act as nucleation centers for the evaporated metals, thus the deposited adatoms are less mobile and the sample grows homogeneously.These two geometries lead to two different types of SIT. Figure 1 compares the behavior of uniform and granular quench condensed films of Pb on a SiO substrate.

show abstract

“…An established technique to study the properties of granular superconductors is quench condensation [2][3][4][5][6]. In this method one performs sequential evaporations on a cryogenically cold substrate under UHV conditions using the following scheme: Metallic leads for four-terminal measurements are prepared on an insulating substrate which is then mounted onto an evacuated measurement probe and immersed in a liquid He bath.…”

mentioning

confidence: 99%

Universal transport in two-dimensional granular superconductors

2002

Self Cite

View full text Add to dashboard Cite

The transport properties of quench condensed granular superconductors are presented and analyzed. These systems exhibit transitions from insulating to superconducting behavior as a function of inter-grain spacing. Superconductivity is characterized by broad transitions in which the resistance drops exponentially with reducing temperature. The slope of the log R versus T curves turns out to be universaly dependent on the normal state film resistance for all measured granular systems. It does not depend on the material, critical temperature, geometry, or experimental set-up. We discuss possible physical scenarios to explain these findings.

show abstract

Two-Dimensional Electrical Conductivity in Quench-Condensed Metal Films

Cited by 214 publications

References 11 publications

Cooper-pair insulator phase in superconducting amorphous Bi films induced by nanometer-scale thickness variations

Cooper-pair insulator phase in superconducting amorphous Bi films induced by nanometer-scale thickness variations

The superconductor insulator transition in systems of ultrasmall grains

Universal transport in two-dimensional granular superconductors

Contact Info

Product

Resources

About