| 1. |
- Bauch, Thilo, 1972, et al.
(författare)
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Correlated quantization of supercurrent and conductance in a superconducting quantum point contact
- 2005
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Ingår i: Physical Review B. ; 71:17, s. 174502-
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the supercurrent and conductance of a superconducting quantum point contact in a superconductor two-dimensional electron gas-superconductor Josephson junction. We observe that the supercurrent and conductance change stepwise in a correlated manner as a function of the gate voltage. This was achieved by simultaneous measurement of the supercurrent and conductance at high bias from the same current voltage characteristic.
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| 2. |
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| 3. |
- 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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| 4. |
- He, Hans, et al.
(författare)
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Highly efficient UV detection in a metal-semiconductor-metal detector with epigraphene
- 2022
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Ingår i: Applied Physics Letters. - : American Institute of Physics Inc.. - 0003-6951 .- 1077-3118. ; 120:19
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Tidskriftsartikel (refereegranskat)abstract
- We show that epitaxial graphene on silicon carbide (epigraphene) grown at high temperatures (T >1850 °C) readily acts as material for implementing solar-blind ultraviolet (UV) detectors with outstanding performance. We present centimeter-sized epigraphene metal-semiconductor-metal (MSM) detectors with a peak external quantum efficiency of η ∼85% for wavelengths λ = 250-280 nm, corresponding to nearly 100% internal quantum efficiency when accounting for reflection losses. Zero bias operation is possible in asymmetric devices, with the responsivity to UV remaining as high as R = 134 mA/W, making this a self-powered detector. The low dark currents Io ∼50 fA translate into an estimated record high specific detectivity D = 3.5 × 1015 Jones. The performance that we demonstrate, together with material reproducibility, renders epigraphene technologically attractive to implement high-performance planar MSM devices with a low processing effort, including multi-pixel UV sensor arrays, suitable for a number of practical applications. © 2022 Author(s).
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| 5. |
- Andersson, Eric, 1992, et al.
(författare)
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Fabrication and electrical transport characterization of high quality underdoped YBa2Cu3O7-δ nanowires
- 2020
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 33:6
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Tidskriftsartikel (refereegranskat)abstract
- We present the fabrication and electrical transport characterization of underdoped YBa2Cu3O7-δnanowires. The nanowires have been realized without any protective capping layer and theyshow transport properties similar to those of the parent thin film, demonstrating that they havenot been damaged by the nanopatterning. The current-voltage characteristics of the underdopednanowires show large hysteretic voltage switching at the critical current, in contrast to theflux-flow like characteristics of optimally doped nanostructures, indicating the formation of aself-stabilizing hot spot. These results open up new possibilities for using the underdopednanowires as single photon detectors and for exploring the underdoped side of the YBa2Cu3O7-δphase diagram at the nanoscale.
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| 6. |
- Andzane, J., et al.
(författare)
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Catalyst-free vapour-solid technique for deposition of Bi2Te3 and Bi2Se3 nanowires/nanobelts with topological insulator properties
- 2015
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 7:38, s. 15935-15944
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Tidskriftsartikel (refereegranskat)abstract
- We present a simple two-stage vapour-solid synthesis method for the growth of bismuth chalcogenide (Bi2Te3, Bi2Se3) topological insulator nanowires/nanobelts by using Bi2Se3 or Bi2Te3 powders as source materials. During the first stage of the synthesis process nanoplateteles, serving as "catalysts" for further nanowire/nanobelt growth, are formed. At a second stage of the synthesis, the introduction of a N-2 flow at 35 Torr pressure in the chamber induces the formation of free standing nanowires/nanobelts. The synthesised nanostructures demonstrate a layered single-crystalline structure and Bi : Se and Bi : Te ratios 40 : 60 at% for both Bi2Se3 and Bi2Te3 nanowires/nanobelts. The presence of Shubnikov de Haas oscillations in the longitudinal magneto-resistance of the nanowires/nanobelts and their specific angular dependence confirms the existence of 2D topological surface states in the synthesised nanostructures.
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| 7. |
- Arpaia, Riccardo, 1985, et al.
(författare)
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Engineering underdoped CuO2 nanoribbons in nm-thick a -axis YBa2Cu3 O7-δ films
- 2024
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Ingår i: Physical Review Materials. - 2475-9953. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- In underdoped cuprate high-Tc superconductors, various local orders and symmetry-breaking states, in addition to superconductivity, reside in the CuO2 planes. The confinement of the CuO2 planes can therefore play a fundamental role in modifying the hierarchy between the various orders and their intertwining with superconductivity. Here we present the growth of a-axis oriented YBa2Cu3O7-δ films, spanning the whole underdoped side of the phase diagram. In these samples, the CuO2 planes are confined by the film thickness, effectively forming unit-cell-thick nanoribbons. The unidirectional confinement at the nanoscale enhances the in-plane anisotropy of the films. By x-ray diffraction and resistance vs temperature measurements, we have discovered the suppression of the orthorhombic-to-tetragonal transition at low dopings, and a very high anisotropy of the normal state resistance in the b-c plane, the latter being connected to a weak coupling between adjacent CuO2 nanoribbons. These findings show that the samples we have grown represent a novel system, different from the bulk, where future experiments can possibly shed light on the rich and mysterious physics occurring within the CuO2 planes.
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| 8. |
- Arpaia, Riccardo, 1985, et al.
(författare)
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Engineering underdoped CuO2 nanoribbons in nm-thick a -axis YBa2Cu3 O7-δ films
- 2024
-
Ingår i: Physical Review Materials. - : American Physical Society. - 2475-9953. ; 8:4
-
Tidskriftsartikel (refereegranskat)abstract
- In underdoped cuprate high-Tc superconductors, various local orders and symmetry-breaking states, in addition to superconductivity, reside in the CuO2 planes. The confinement of the CuO2 planes can therefore play a fundamental role in modifying the hierarchy between the various orders and their intertwining with superconductivity. Here we present the growth of a-axis oriented YBa2Cu3O7-δ films, spanning the whole underdoped side of the phase diagram. In these samples, the CuO2 planes are confined by the film thickness, effectively forming unit-cell-thick nanoribbons. The unidirectional confinement at the nanoscale enhances the in-plane anisotropy of the films. By x-ray diffraction and resistance vs temperature measurements, we have discovered the suppression of the orthorhombic-to-tetragonal transition at low dopings, and a very high anisotropy of the normal state resistance in the b-c plane, the latter being connected to a weak coupling between adjacent CuO2 nanoribbons. These findings show that the samples we have grown represent a novel system, different from the bulk, where future experiments can possibly shed light on the rich and mysterious physics occurring within the CuO2 planes.
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| 9. |
- Arpaia, Riccardo, 1985, et al.
(författare)
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High-temperature superconducting nanowires for photon detection
- 2015
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Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 509, s. 16-21
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Tidskriftsartikel (refereegranskat)abstract
- The possible use of high-temperature superconductors (HTS) for realizing superconducting nanowire single-photon detectors is a challenging, but also promising, aim because of their ultrafast electron relaxation times and high operating temperatures. The state-of-the-art HTS nanowires with a 50-nm thickness and widths down to 130 nm have been fabricated and tested under a 1550-nm wavelength laser irradiation. Experimental results presenting both the amplitude and rise times of the photoresponse signals as a function of the normalized detector bias current, measured in a wide temperature range, are discussed. The presence of two distinct regimes in the photoresponse temperature dependence is clearly evidenced, indicating that there are two different response mechanisms responsible for the HTS photoresponse mechanisms.
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| 10. |
- Arpaia, Riccardo, 1985, et al.
(författare)
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Highly homogeneous YBCO/LSMO nanowires for photoresponse experiments
- 2014
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- By using nanolithography and a soft etching procedure, we have realized YBa2Cu3O7-x/La0.7Sr0.3MnO3 (YBCO/LSMO) nanowires, with cross sections down to 100 x 50 nm(2) that ensure the cover age of areas up to 10 x 30 mu m(2). The LSMO layer acts as a capping for YBCO, minimizing the degradation of the superconducting properties taking place during the patterning; moreover, as a ferromagnetic manganite, it is expected to accelerate the relaxation dynamics of quasiparticles in YBCO, making such a system potentially attractive for applications in superconducting ultrafast optoelectronics. The reproducibility of the values of the critical current densities measured in different devices with the same geometry makes our nanowires ideal candidates for photoresponse experiments. First measurements have shown a satisfactory photoresponse from YBCO/LSMO devices.
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