Nonmetallic conductivity of epitaxial monolayers of Ag at low temperatures

Henzler, M.; Lüer, T.; Burdach, A.

doi:10.1103/physrevb.58.10046

Cited by 38 publications

(33 citation statements)

References 24 publications

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“…The gray line in Figure 1 corresponds to the temperature dependence of the conductivity of a 1.2-nm-thick, pure Ag film. In accord with previous studies, [20] the low conductivity of pure Ag films in the low-temperature region up to 160 K stems from a disordered structure formed during the deposition because the surface diffusion of the Ag atoms is suppressed. With an increase in temperature above 160 K, Ag grains start to form a continuous crystalline film with a rearrangement of atoms and exhibit an abrupt increase in conductivity.…”

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confidence: 89%

Noble Metal Intercalated Fullerene Fabricated by Low‐Temperature Co‐deposition

et al. 2009

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The high potential of metal-doped fullerenes (C 60 ) as hydrogen-storage materials has recently been discussed intensively. [1][2][3][4][5][6] Owing to its unique mechanical properties, such as high surface area and porosity, C 60 is believed to be one of the most promising hydrogen-storage systems. Utilization of noble or transition metals as dopants for C 60 will lead to stronger interactions with hydrogen molecules based on Dewar-Kubas interactions, reaching the target of the hydrogen-adsorption capacity set by the US Department of Energy (6.5 wt%). [4][5][6] However, so far all of the reports on noble or transition metal-doped C 60 are restricted to theoretical discussions because of the difficulties in the fabrication arising from the highly cohesive characteristics of metal atoms and, thus, the actual fabrication of these materials has been highly desired.Noble metal-doped C 60 will also provide a route to addressing the possibility of superconductivity in these systems, suggested by the observation of a gap opening at the Fermi level of a C 60 monolayer on Ag, [7] which triggered a large number of studies on the structural and electronic properties of noble metal-C 60 systems. [8][9][10] Since most studies have been restricted to the 2D configuration (bilayer) of noble metals and C 60 because of cohesive characteristics of noble metals, [8][9][10][11][12][13][14] it has been difficult to address directly the possibility of superconductivity in these systems. Furthermore, several puzzling issues, such as various bonding characteristics between metals and C 60 [13,14] or negative and positive changes in work functions depending on substrates, [14] have not yet been well understood, thus, the noble metal-doped C 60 is expected to serve as a 3D platform for further investigation of these issues.Despite these promising and intriguing properties, fabrication of noble or transition metal-doped C 60 has been one of the fundamental challenges. The high cohesive energy of metals (e.g., 3.48, 2.93, and 3.81 eV, for Cu, Ag, and Au, respectively) [15] compared to that of alkali or alkaline earth metals (e.g., 1.11, 0.93, 1.87, and 1.90 eV, for Na, K, Sr, and Ba, respectively) [15] leads to aggregation of metal atoms separated from a C 60 phase. The co-deposition of metals and C 60 is reported as an effective way to fabricate metal-C 60 mixed films. [16,17] In these previous studies, however, metals and C 60 were deposited on a substrate kept at room temperature, where both metal atoms and C 60 molecules have quite high mobility, resulting in aggregation of metals separated from a C 60 phase.To suppress the diffusion and aggregation, we utilize a substrate maintained at low temperature in the present study. We focus on the Ag-C 60 system because not only the possibility of novel superconductivity [7] but also the improvement of hydrogen adsorption with Ag has been reported. [18,19] In addition, the ion radius of Ag þ (0.129 nm) is comparable with that of alkali or alkaline earth metals, ranging from 0.090 to 0.181 nm, w...

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confidence: 89%

Noble Metal Intercalated Fullerene Fabricated by Low‐Temperature Co‐deposition

et al. 2009

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“…For thin films at low temperatures weak localization has been observed as quantum interference effect of the backscattered electrons. [1][2][3] Very thin films at low temperatures, however, cannot be described along these lines, since their conductance is too low for weak localization and shows some kind of metalinsulator transition for a temperature range from 100 to 15 K. 4 Therefore some change in scattering mechanism has to occur.…”

Section: Introductionmentioning

confidence: 99%

Magnetoconductivity of ultrathin epitaxial Ag films on Si(111)7×7at low temperatures

1999

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Ultrathin epitaxial Ag films on Si͑111͒ 7ϫ7 have been shown to have at approximately 4 K a very low conductance, whereas at 100 K the metallic conductivity is evident. Therefore the magnetoconductance has been used to identify the different scattering mechanisms. The conductance and the magnetoconductance have been measured in situ with four-point probes in van der Pauw arrangement. For thicknesses from 1.8 to 20 ML different scattering mechanisms have been revealed in the temperature range from approximately 4 to 20 K and magnetic fields from Ϫ4 T to ϩ4 T perpendicular to the sample surface. Whereas for films thicker than 3 ML the weak localization and antilocalization provide a complete description, the thinnest films show properties not yet described quantitatively by any theory.

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“…These findings are in agree- ment with previous investigations of Ag film conductance on a macroscopic scale. 27 Here a nonmetallic conductivity for a similar thin Ag-film structure has been reported using a macroscopic four-point probe technique in a Van-der-Pauw geometry. Consistent with our STS results, the authors identified the CB limited tunneling between the grains as a likely mechanism for the transport in this system.…”

Section: Ag Multilayers: the Role Of The Wetting Layermentioning

confidence: 99%

“…Consistent with our STS results, the authors identified the CB limited tunneling between the grains as a likely mechanism for the transport in this system. 27 The transport characteristics of a double junction barrier change to single barrier properties, if Ag islands are evaporated onto an Ag ͱ 3 ϫ ͱ 3 reconstruction. The inset of Fig.…”

Section: Ag Multilayers: the Role Of The Wetting Layermentioning

confidence: 99%

Coulomb blockade effects in Ag/Si(111): The role of the wetting layer

2009

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Single and double barrier structures have been realized with Ag nanostructures grown on Si͑111͒ in combination with scanning tunneling microscopy. The series connection of a Schottky ͑SB͒ and tunneling barrier mimics a double barrier structure showing Coulomb blockade oscillations as revealed by scanning tunneling spectroscopy ͑STS͒. Although the SB remains in presence of a Ag ͱ 3 ϫ ͱ 3 reconstruction, the dI / dV characteristic turns into a single barrier structure. The Ag reconstruction provides a sufficiently high electron mobility capturing intrinsic defects which shortens the resistance of the SB. These results show that vertical transport properties, as measured with STS, are not only controlled by the structure and the bonding on the atomic scale, but depend strongly on the lateral properties of the interface as well.

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Nonmetallic conductivity of epitaxial monolayers of Ag at low temperatures

Cited by 38 publications

References 24 publications

Noble Metal Intercalated Fullerene Fabricated by Low‐Temperature Co‐deposition

Noble Metal Intercalated Fullerene Fabricated by Low‐Temperature Co‐deposition

Magnetoconductivity of ultrathin epitaxial Ag films on Si(111)7×7at low temperatures

Coulomb blockade effects in Ag/Si(111): The role of the wetting layer

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