| 31. |
- Black-Schaffer, Annica M., et al.
(författare)
-
Model Evidence of a Superconducting State with a Full Energy Gap in Small Cuprate Islands
- 2013
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 110:19, s. 197001-
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate subdominant order parameters stabilizing at low temperatures in nanoscale high-Tc cuprate islands, motivated by the recent observation of a fully gapped state in nanosized YBa2Cu3O7-δ[D. Gustafsson et al., Nature Nanotech. 8, 25 (2013)]. Using complementary quasiclassical and tight-binding Bogoliubov–de Gennes methods, we show on distinctly different properties dependent on the symmetry being dx2-y2 þ is or dx2-y2 þ idxy. We find that a surface-induced dx2-y2 þ is phase creates a global spectroscopic gap which increases with an applied magnetic field, consistent with experimental observation.
|
|
| 32. |
- Born, D., et al.
(författare)
-
CaBaCuO ultrathin films and junctions
- 2007
-
Ingår i: IEEE Transactions on Applied Superconductivity. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2515 .- 1051-8223. ; 17:2/3, s. 3581-3584
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated transport properties of ultrathin CaBaCuO (CBCO) bridges, focusing on vortex dynamics, and Josephson bicrystal junctions. The CBCO films used are composed of a stacking sequence of two structural subunits having different functions, namely a Ba-based charge reservoir (CR) block and a Ca-based infinite layer (IL) superconducting block. SQUID microscopy investigations of these films provide Pearl lengths A more than the bridge widths. Measuring current-voltage characteristics we found evidence that at high temperatures the vortices are thermally activated at the edge of the bridge and pushed in, causing dissipation and a power-law dependence of the voltage from the current. At lower temperatures, the experimental curves change their shape. We compared these data with the predicted behavior for vortex quantum tunneling and we found very good agreement. Moreover, we have realized Josephson junctions composed of only a few superconducting CuO2 planes. The CBCO films used in these experiments are only 8 nm thick and have six superconducting CUO2 planes. The simple structure of the GB allows a reliable estimation of the coupling along the ab planes of the CuO2. We calculate for 24 degrees symmetric and asymmetric cases a critical current density per plane of about (1-3) kA/cm(2).
|
|
| 33. |
|
|
| 34. |
- Calavalle, Francesco, et al.
(författare)
-
Tailoring Superconductivity in Large-Area Single-Layer NbSe2 via Self-Assembled Molecular Adlayers
- 2021
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 21:1, s. 136-143
-
Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional transition metal dichalcogenides (TMDs) represent an ideal testbench for the search of materials by design, because their optoelectronic properties can be manipulated through surface engineering and molecular functionalization. However, the impact of molecules on intrinsic physical properties of TMDs, such as superconductivity, remains largely unexplored. In this work, the critical temperature (TC) of large-area NbSe2 monolayers is manipulated, employing ultrathin molecular adlayers. Spectroscopic evidence indicates that aligned molecular dipoles within the self-assembled layers act as a fixed gate terminal, collectively generating a macroscopic electrostatic field on NbSe2. This results in an ∼55% increase and a 70% decrease in TC depending on the electric field polarity, which is controlled via molecular selection. The reported functionalization, which improves the air stability of NbSe2, is efficient, practical, up-scalable, and suited to functionalize large-area TMDs. Our results indicate the potential of hybrid 2D materials as a novel platform for tunable superconductivity.
|
|
| 35. |
- Cedergren, Karin, 1975, et al.
(författare)
-
Biepitaxial YBa2Cu3O7-x 0-pi Josephson junctions
- 2010
-
Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 23:3, s. Article Number: 034027-
-
Tidskriftsartikel (refereegranskat)abstract
- We present measurements performed on YBa2Cu3O7-x '0' and '0-pi' Josephson junctions fabricated using the biepitaxial technique with SrTiO3 as substrate and CeO2 as seed layer. Measurements of the critical current as a function of external magnetic field clearly show complementary behavior of the two kinds of junctions. Our results unambiguously show that the d-wave nature of the order parameter dominates the current transport across the junctions despite the faceting on the microscale along the grain boundary line.
|
|
| 36. |
- Cedergren, Karin, 1975, et al.
(författare)
-
Interplay between Static and Dynamic Properties of Semifluxons in YBa2Cu3O7−δ 0−π Josephson Junctions
- 2010
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 104:17, s. 177003 -
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the static and dynamic properties of long YBa2Cu3O7-delta 0-pi Josephson junctions and compared them with those of conventional 0 junctions. Scanning SQUID microscope imaging has revealed the presence of a semifluxon at the phase discontinuity point in 0-pi Josephson junctions. Zero field steps have been detected in the current-voltage characteristics of all junctions. Comparison with simulation allows us to attribute these steps to fluxons traveling in the junction for conventional 0 junctions and to fluxon-semifluxon interactions in the case of 0-pi Josephson junctions.
|
|
| 37. |
- Charpentier, Sophie, 1983, et al.
(författare)
-
Hot spot formation in electron-doped PCCO nanobridges
- 2016
-
Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 94:6
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the transport properties of optimally doped Pr2-xCexCuO4-δ (PCCO) nanobridges with width down to 100 nm. The critical current density of the nanobridges approaches the Ginzburg-Landau theoretical limit, which demonstrates nanostructures with properties close to the as-grown films. The current voltage characteristics are hysteretic with a sharp voltage switch, of the order of a few millivolts, that we interpret with the occurrence of a hot spot formation. The values of the retrapping current and the voltage switch obtained by modeling the heat transport in the nanobridges are very close to the experimental ones. This feature, together with the extremely short recombination times, make PCCO nanostructures attractive candidates for ultrafast single photon detectors.
|
|
| 38. |
- Charpentier, Sophie, 1983, et al.
(författare)
-
Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator
- 2017
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p(x) + ip(y) wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral px + ipy component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and pi coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.
|
|
| 39. |
|
|
| 40. |
|
|
