Electron conduction through quasi-one-dimensional indium wires on silicon

Uchihashi, Takashi; Ramsperger, U.

doi:10.1063/1.1483929

Cited by 67 publications

(59 citation statements)

References 11 publications

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“…Shortly after the first observation of superconducting energy gap by means of scanning tunneling spectroscopy (STS) [1], insitu electrical transport measurements have demonstrated that supercurrents can travel over macroscopic distances in those surface systems [2][3][4]. The finding of the macroscopic supercurrents was unexpected, because the surfaces always have atomic steps that may decouple metallic films grown on the terraces [6,7]. The temperature dependence of the critical current suggests that the supercurrents flow across the atomic steps with the help of the Josephson effect [2].…”

Section: Introductionmentioning

confidence: 99%

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Yoshizawa

Kim

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

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We performed low-temperature scanning tunneling microscopy and spectroscopy on Si(111)-( √ 7× √ 3)-In in magnetic fields. Superconducting vortices were observed by mapping zero-bias conductance in an area consisting of flat terraces separated by atomic steps. While vortices in the terrace regions have an isotropic shape with a normal-state core, those at the atomic steps have anisotropic shapes and the superconductivity is only weakly suppressed in the cores. These properties are understood as a crossover from a normal vortex to a Josephson vortex. We conclude that the atomic steps work as Josephson junctions limiting the density of supercurrents.

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Section: Introductionmentioning

confidence: 99%

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Yoshizawa

Kim

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

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“…Grooves are visible along step δ, indicating that the superconducting indium layers did not grow up to the step edge. This should result in a weak electronic coupling between the upper and lower terraces [14] and hence in a low J c /J 0 . In contrast, such a structure is nearly absent for step α, which helps to establish a stronger interterrace coupling.…”

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confidence: 99%

“…Atomic steps are considered to strongly affect electron transport phenomena, because they potentially decouple neighboring surface terraces [12][13][14][15]. This could prevent superconducting currents from running over a long distance.…”

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confidence: 99%

Imaging Josephson Vortices on the Surface SuperconductorSi(111)−(7×3)
Yoshizawa
¹
,
Kim
²
,
Kawakami
³

et al. 2014
Phys. Rev. Lett.
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75
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We have studied the superconducting Si(111)-( √ 7 × √ 3)-In surface using a 3 He-based lowtemperature scanning tunneling microscope (STM). Zero-bias conductance (ZBC) images taken over a large surface area reveal that vortices are trapped at atomic steps after magnetic fields are applied. The crossover behavior from Pearl to Josephson vortices is clearly identified from their elongated shapes along the steps and significant recovery of superconductivity within the cores. Our numerical calculations combined with experiments clarify that these characteristic features are determined by the relative strength of the interterrace Josephson coupling at the atomic step.PACS numbers: 74.25. Ha,74.55.+v,74.50.+r The recent discovery of superconductivity in silicon surface reconstructions with metal adatoms was an unexpected surprise, because they are regarded as one of the thinnest two-dimensional (2D) materials ever possible [1][2][3][4][5]. This class of surface 2D materials has now become relevant for extensive superconductor researches in progress [6][7][8][9]. Notably, these new studies have been advanced by surface analytical techniques such as scanning tunneling microscopy (STM) [1,5,7,8] and ultrahigh vacuum (UHV)-compatible transport measurement [2-4, 10, 11].One ubiquitous feature of these surface systems is the presence of atomic steps. Atomic steps are considered to strongly affect electron transport phenomena, because they potentially decouple neighboring surface terraces [12][13][14][15]. This could prevent superconducting currents from running over a long distance. The presence of supercurrents through atomic steps has indeed been demonstrated by direct electron transport measurements [2][3][4], and recent experiments indicated that atomic steps work as Josephson junctions [2,5]. Nevertheless, direct evidence of Josephson coupling has not been obtained yet, and possible local variation of its strength has remained an open issue. This problem is also closely related to Josephson junctions formed at the grain boundaries in thin films of high-T c cuprates, which are of technological importance [16,17].In this Letter, we report on compelling evidence of the Josephson coupling at atomic steps on the surface superconductor Si (111)Zero-bias conductance (ZBC) images taken with a low-temperature (LT) STM reveal that vortices are present at atomic steps after magnetic fields are applied. The crossover behavior from Pearl to Josephson vortices is evident from their characteristic elongated shapes and significant recovery of superconductivity within their cores. This identification is strongly supported by our numerical calculations, which clarify their dependence on the interterrace Josephson coupling at the atomic step.The experiment was performed using a UHV-LT-STM constructed at the Institute of Solid State Physics, University of Tokyo. The STM head was accommodated within a 3 He-based cryostat combined with a solenoid superconducting magnet, where magnetic field was applied in the normal direction to the sampl...

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“…ð8 Â 2Þ phase transition, but also the LT ground-state and its properties remain controversial. While the RT ð4 Â 1Þ phase is a quasi-1D metal [12,16,22], it has been variously suggested that the LT ð8 Â 2Þ phase is metallic, but with a lower density of states at the Fermi level [19,20,23], semimetallic [19], and semiconducting with a fundamental energy gap of 0.1-0.3 eV [15][16][17][18]21]. Most ab initio calculations predict the nanowire ground state to be characterized by the formation of In trimers (cf.…”

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Structure of Si(111)-In Nanowires Determined from the Midinfrared Optical Response

Chandola

Hinrichs²,

Gensch³

et al. 2009

Phys. Rev. Lett.

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The anisotropic optical response of Sið111Þ À ð4 Â 1Þ=ð8 Â 2Þ-In in the midinfrared, where ab initio studies predict significant changes in the band structure between competing models of this important quasi-1D system, has been measured using infrared spectroscopic ellipsometry (IRSE) and reflection anisotropy spectroscopy (RAS). Both IRSE and RAS of the (8 Â 2) phase show that the anisotropic Drude tail of the (4 Â 1) phase is replaced by two peaks at 0.50 and 0.72 eV, which appear in ab initio optical response calculations for the hexagon model of the (8 Â 2) structure, but not the trimer model.

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Electron conduction through quasi-one-dimensional indium wires on silicon

Cited by 67 publications

References 11 publications

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Imaging Josephson Vortices on the Surface SuperconductorSi(111)−(7×3)
Yoshizawa
¹
,
Kim
²
,
Kawakami
³

et al. 2014
Phys. Rev. Lett.
Self Cite
75
3
57
0
View full text Add to dashboard Cite

Structure of Si(111)-In Nanowires Determined from the Midinfrared Optical Response

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Electron conduction through quasi-one-dimensional indium wires on silicon

Cited by 67 publications

References 11 publications

Impact of Surface Conditions on the Superconductivity of Si(111)-(&radic;7 &times; &radic;3)-In

Impact of Surface Conditions on the Superconductivity of Si(111)-(&radic;7 &times; &radic;3)-In

Imaging Josephson Vortices on the Surface SuperconductorSi(111)−(7×3)Yoshizawa1, Kim2, Kawakami3 et al. 2014Phys. Rev. Lett.Self Cite753570View full textAdd to dashboardCite

Structure of Si(111)-In Nanowires Determined from the Midinfrared Optical Response

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Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Imaging Josephson Vortices on the Surface SuperconductorSi(111)−(7×3)
Yoshizawa
¹
,
Kim
²
,
Kawakami
³

et al. 2014
Phys. Rev. Lett.
Self Cite
75
3
57
0
View full text Add to dashboard Cite