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Plecenı́k, A.; Grajcar, M.; Beňačka, Š.; Seidel, P.; Pfuch, Andreas

doi:10.1103/physrevb.49.10016

Cited by 213 publications

(186 citation statements)

References 15 publications

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“…In this model, two parameters are introduced to describe the necessary physical quantities, i.e., the effective potential barrier (Z) and the superconducting energy gap (∆). As an extension, the quasiparticle energy E is replaced by E − iΓ, where Γ is the broadening parameter characterizing the finite lifetime of the quasiparticles due to inelastic scattering near the N/S micro-constriction [34,35]. In a real N-I-S junction configuration, total tunneling conductance spectrum includes the integration over the solid angle.…”

Section: B Theoretical Model -S-wave Btk Theorymentioning

confidence: 99%

Distinct pairing symmetries inNd1.85Ce0.15CuO4−yandLa1.89

et al. 2005

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We used point-contact tunnelling spectroscopy to study the superconducting pairing symmetry of electron-doped N d1.85Ce0.15CuO4−y (NCCO) and hole-doped La1.89Sr0.11CuO4 (LSCO). Nearly identical spectra without zero bias conductance peak (ZBCP) were obtained on the (110) and (100) oriented surfaces (the so-called nodal and anti-nodal directions) of NCCO. In contrast, LSCO showed a remarkable ZBCP in the nodal direction as expected from a d-wave superconductor. Detailed analysis reveals an s-wave component in the pairing symmetry of the NCCO sample with ∆/kBTc = 1.66, a value remarkable close to that of a weakly coupled BCS superconductor. We argue that this s-wave component is formed at the Fermi surface pockets centered at (±π,0) and (0,±π) although a d-wave component may also exist.

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Section: B Theoretical Model -S-wave Btk Theorymentioning

confidence: 99%

Distinct pairing symmetries inNd1.85Ce0.15CuO4−yandLa1.89

et al. 2005

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“…One representative spectrum in the intermediate regime is that is traditionally used to analyze Andreev reflection spectra obtained on conventional BCS superconductors [20]. This might be due to a large inelastic broadening parameter at the interface [21] or due to the existence of multiple gaps [22]. Nevertheless, the position of the peaks provide an approximate estimate of the gap [20].…”

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confidence: 99%

Unconventional superconductivity at mesoscopic point contacts on the 3D Dirac semimetal Cd3As2

et al. 2015

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Since the three dimensional (3D) Dirac semi-metal Cd 3 As 2 exists close to topological phase boundaries, in principle it should be possible to drive it into exotic new phases, like topological superconductors, by breaking certain symmetries. Here we show that the mesoscopic point-contacts between silver (Ag) and Cd 3 As 2 exhibit superconductivity up to a critical temperature (onset) of 6 K while neither Cd 3 As 2 nor Ag are superconductors. A gap amplitude of 6.5 meV is measured spectroscopically in this phase that varies weakly with temperature and survives up to a remarkably high temperature of 13 K indicating the presence of a robust normal-state pseudogap. The observations indicate the emergence of a new unconventional superconducting phase that exists only in a quantum mechanically confined region under a point-contact between a Dirac semi-metal and a normal metal. * These authors contributed equally to the work † ashok@chemistry.iitd.ac.in ‡ goutam@iisermohali.ac.in 1 arXiv:1410.2072v1 [cond-mat.supr-con]

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“…The peaks are fitted well by the BlonderTinkham-Klapwijk (BTK) theory of SN interfaces, (1) where f (E) is the Fermi function, A(E) and B(E) are probabilities of Andreev and normal reflection, and Γ characterizes lifetime broadening 30 . The interface barrier strength Z accounts for elastic scattering, including reflections due to Fermi wavevector mismatch 27 .…”

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confidence: 99%

Gate-tunable superconducting weak link and quantum point contact spectroscopy on a strontium titanate surface

et al. 2014

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Two-dimensional electron systems in gallium arsenide and graphene have enabled ground-breaking discoveries in condensed-matter physics, in part because they are easily modulated by voltages on nanopatterned gate electrodes. Electron systems at oxide interfaces hold a similarly large potential for fundamental studies of correlated electrons and novel device technologies 1-3 , but typically have carrier densities too large to control by conventional gating techniques. Here we present a quantum transport study of a superconducting strontium titanate (STO) interface, enabled by a combination of electrolyte 4-7 and metal-oxide gating. Our structure consists of two superconducting STO banks flanking a nanoscale STO weak link, which is tunable at low temperatures from insulating to superconducting behaviour by a local metallic gate. At low gate voltages, our device behaves as a quantum point contact that exhibits a minimum conductance plateau of e 2 /h in zero applied magnetic field, half the expected value for spin-degenerate electrons, but consistent with predictions 8-12 and experimental signatures 13-18 of a magnetically ordered ground state. The quantum point contact mediates tunnelling between normal and superconducting regions, enabling lateral tunnelling spectroscopy of the local superconducting state. Our work provides a generic scheme for quantum transport studies of STO and other surface electron liquids.Transition metal oxides exhibit electronic ground states not seen in conventional semiconductors 2,3 . For instance, the interface between lanthanum aluminate and strontium titanate 19 -two non-magnetic band insulators-hosts superconductivity 20 and magnetism [13][14][15][16][17][18] . Rashba spin-orbit coupling at conductive STO interfaces 21 has led to predictions of unconventional superconducting states 10 , and of helical wires and Majorana fermions in nanoscale STO channels 11 . Furthermore, nanoscale lateral control of carriers could allow fabrication of gate-tunable, single-material Josephson junctions and superconducting quantum interference devices, as well as mesoscopic devices. However, few experiments on nanostructures in STO systems exist: superconductivity has been demonstrated in submicron regions tunable with a global back gate 22 , and channels sketched by a nanoscale tip show superconducting features 23 . In this work, we demonstrate the first realization of an all-STO, gate-tunable superconducting weak link. We tune our device to the ballistic 1D limit and perform superconducting spectroscopy that agrees with BCS weak-coupling expectations and previous work 24 .Undoped STO is a band insulator. Inducing a two-dimensional (2D) electron density near 10 13 cm −2 creates a metal, and several times that density creates an optimally doped superconducting state 4 . To modulate the density on this scale, we use the electric double-layer transistor technique [4][5][6][7] . A schematic of our sample is shown in Fig. 1a. A single crystal of TiO 2 -terminated (100) SrTiO 3 is patterned with ohmic conta...

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Finite-quasiparticle-lifetime effects in the differential conductance ofBi2Sr2

Cited by 213 publications

References 15 publications

Distinct pairing symmetries inNd1.85Ce0.15CuO4−yandLa1.89

Distinct pairing symmetries inNd1.85Ce0.15CuO4−yandLa1.89

Unconventional superconductivity at mesoscopic point contacts on the 3D Dirac semimetal Cd3As2

Gate-tunable superconducting weak link and quantum point contact spectroscopy on a strontium titanate surface

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