| 1. |
- Charpentier, Sophie, 1983, et al.
(författare)
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Hot spot formation in electron-doped PCCO nanobridges
- 2016
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 94:6
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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.
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| 2. |
- Arpaia, Riccardo, 1985, et al.
(författare)
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Resistive state triggered by vortex entry in YBa2Cu3O7-delta nanostructures
- 2014
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Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 506, s. 165-168
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Tidskriftsartikel (refereegranskat)abstract
- We have realized YBa2Cu3O7-delta nanowires and nano Superconducting Quantum Interference Devices (nanoSQUID). The measured temperature dependence of the wire resistances below the superconducting transition temperature has been analyzed using a thermally activated vortex entry model valid for wires wider than the superconducting coherence length. The extracted zero temperature values of the London penetration depth, lambda(0) similar or equal to 270 +/- 15 nm, are in good agreement with the value obtained from critical current modulations as a function of an externally applied magnetic field in a nanoSQUID implementing two nanowires.
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| 3. |
- Baghdadi, Reza, 1984, et al.
(författare)
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Fabricating Nanogaps in YBa2Cu3O7-delta for Hybrid Proximity-Based Josephson Junctions
- 2015
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Ingår i: Physical Review Applied. - 2331-7019. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- The advances of nanotechnologies applied to high-critical-temperature superconductors (HTSs) have recently given a huge boost to the field, opening new prospectives for their integration in hybrid devices. The feasibility of this research goes through the realization of HTS nanogaps with superconductive properties close to the as-grown bulk material at the nanoscale. Here we present a fabrication approach allowing the realization of YBa2Cu3O7-delta (YBCO) nanogaps with dimensions as small as 35 nm. To assess the quality of the nanogaps, we measure, before and after an ozone treatment, the current-voltage characteristics and the resistance versus temperature of YBCO nanowires with various widths and lengths, fabricated by using different lithographic processes. The analysis of the superconducting transition with a thermally activated vortex-entry model allows us to determine the maximum damage the nanowires undergo during the patterning which relates to the upper bound for the dimension of the nanogap. We find that the effective width of the nanogap is of the order of 100 nm at the superconducting transition temperature while retaining the geometrical value of about 35 nm at lower temperatures. The feasibility of the nanogaps for hybrid Josephson devices is demonstrated by bridging them with thin Au films. We detect a Josephson coupling up to 85 K with an almost ideal magnetic-field response of the Josephson current. These results pave the way for the realization of complex hybrid devices, where tiny HTS nanogaps can be instrumental to study the Josephson effect through barriers such as topological insulators or graphene.
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| 4. |
- galletti, luca, 1986, et al.
(författare)
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High-Transparency Al/Bi2Te3 Double-Barrier Heterostructures
- 2017
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated highly transparent Al/Bi2Te3/Al superconductor/normal metal/superconductor double-barrier heterostructures. Transport measurements reveal the presence of multiple Andreev reflections related to two distinct energy gaps that we identify as the induced superconducting gap in the two electrodes. The realization of high-transparency Josephson junctions with topological insulators is an important step towards the study of topological superconductivity and Majorana fermions.
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| 5. |
- Golubev, D., et al.
(författare)
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Effect of heating on critical current of YBCO nanowires
- 2014
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Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 506, s. 174-177
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Tidskriftsartikel (refereegranskat)abstract
- We discuss transport of heat in YBCO nanowires and its implications to their superconducting properties. We find under which conditions the central part of a nanowire may turn normal. We demonstrate that in long wires it may happen at currents much lower than the theoretical value of superconducting critical current. We derive a simple formula for the corresponding threshold current in terms of the heat transport parameters of YBCO. Our results may be interesting in view of potential applications of YBCO nanowires in detectors of radiation.
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| 6. |
- Kalaboukhov, Alexei, 1975, et al.
(författare)
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Homogeneous superconductivity at the LaAlO3/SrTiO3 interface probed by nanoscale transport
- 2017
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 96:18
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Tidskriftsartikel (refereegranskat)abstract
- An interface between LaAlO3 and SrTiO3 (LAO/STO) may host two-dimensional superconductivity, strong spin-orbit coupling, and magnetic ordering. There are indications that the interfacial superconducting layer is nonhomogeneous at the nanoscale. The presence of inhomogeneities may have strong implications on the superconducting transport properties and lead to formation of weak links between superconducting regions. In this paper, we report on the temperature and magnetic field dependence of superconducting transport in single nanowires and nanorings fabricated in a LAO/STO interface. The analysis of data proves that our nanostructures behave like uniform superconducting filaments carrying a critical current close to the theoretical Ginzburg-Landau depairing limit. Furthermore, we unexpectedly find an enhancement of the critical current of LAO/STO nanowires and nanorings at low temperature when a magnetic field is applied. Our results point towards the coexistence of a homogeneous interfacial superconductivity and spatially separated magnetism at the LAO/STO interface.
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| 7. |
- Trabaldo, Edoardo, 1990, et al.
(författare)
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Transport and noise properties of YBCO nanowire based nanoSQUIDs
- 2019
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 32:7
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Forskningsöversikt (refereegranskat)abstract
- The development of quantum limited magnetic flux sensors has recently gained a lot of attention for the possibility of detecting the magnetic moment of nanoscaled systems. Here, the ultimate goal is the observation of a single spin. Such sensors are of fundamental importance for applications, ranging from spintronics and spin-based quantum information processing, to fundamental studies of nano-magnetism in molecules and magnetic nanoclusters. A nano-scale superconducting quantum interference device (nanoSQUID) is indeed a promising candidate to reach this ambitious goal. Nanowires, fabricated of high critical temperature superconductors (HTS), have been shown to be a valid candidate for the realization of nanoSQUIDs. A crucial requirement to achieve the necessary flux sensitivity and spatial resolution, is a SQUID loop on the nanometer scale. Moreover, HTS nanowire-based SQUIDs in combination with large area pickup loops or flux transformers might become instrumental in magnetometer applications, such as magneto encephalography and low field magnetic resonance imaging, where low intrinsic magnetic field noise is required. In this review we will give a survey on the state of the art of YBa2Cu3O7-delta thin film nanowires and their implementation in low noise nanoSQUIDs and magnetometers.
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