Search results for "COPI"
showing 10 items of 2618 documents
Rapid assessment of drug abuse prevention needs for youth in small Spanish municipalities: Coping with resource limitations
2006
This study evaluates the drug abuse prevention needs for Spanish youth in municipalities with a population below 7,000 inhabitants in the province of Valencia, Spain. The primary goal of the project was to generate policy and to identify possible courses of drug prevention in these towns. The project utilized the basic RARE model. Grounded Theory was used to frame the qualitative analysis. Interviews with local cultural experts provided strong evidence that many specifically mandated prevention needs are not adequately covered in small municipalities. The data emphasizes the ways in which young people are critical of the prevention actions directed at them. The recommended programs emphasi…
Intraductal aspiration: a promising new tissue-sampling technique for the diagnosis of suspected malignant biliary strictures
2012
Brushing is the most commonly used technique for biliary sampling at ERCP, despite its limited sensitivity. To evaluate intraductal aspiration (IDA) as a new combined endoscopic technique for cytodiagnosis, its cellular adequacy, diagnostic accuracy for cancer detection, feasibility, and safety. Prospective, observational study. Single tertiary referral center. IDA cellular adequacy, diagnostic accuracy for cancer detection, feasibility, and safety. From April 2009 to September 2010, 42 consecutive patients with suspected malignant biliary stricture underwent ERCP, with tissue sampling obtained with IDA. IDA included performance of standard brushing in all patients. After standard brushing,…
Phase-dependent dissipation and supercurrent of a graphene-superconductor ring under microwave irradiation
2020
A junction with two superconductors coupled by a normal metal hosts Andreev bound states whose energy spectrum is phase-dependent and exhibits a minigap, resulting in a periodic supercurrent. Phase-dependent dissipation also appears at finite frequency due to relaxation of Andreev bound states. While dissipation and supercurrent versus phase have previously been measured near thermal equilibrium, their behavior in nonequilibrium is still elusive. By measuring the ac susceptibility of a graphene-superconductor junction under microwave irradiation, we find supercurrent response deviates from adiabatic ac Josephson effect as irradiation frequency is larger than relaxation rate. Notably, when i…
Giant negative magnetoresistance driven by spin-orbit coupling at the LAO/STO interface
2014
The LAO/STO interface hosts a two-dimensional electron system that is unusually sensitive to the application of an in-plane magnetic field. Low-temperature experiments have revealed a giant negative magnetoresistance (dropping by 70\%), attributed to a magnetic-field induced transition between interacting phases of conduction electrons with Kondo-screened magnetic impurities. Here we report on experiments over a broad temperature range, showing the persistence of the magnetoresistance up to the 20~K range --- indicative of a single-particle mechanism. Motivated by a striking correspondence between the temperature and carrier density dependence of our magnetoresistance measurements we propos…
Resistive state of SFS Josephson junctions in the presence of moving domain walls
2019
We describe resistive states of the system combining two types of orderings - superconducting and ferromagnetic one. It is shown that in the presence of magnetization dynamics such systems become inherently dissipative and in principle cannot sustain any amount of the superconducting current because of the voltage generated by the magnetization dynamics. We calculate generic current-voltage characteristics of a superconductor/ferromagnet/superconductor Josephson junction with an unpinned domain wall and find the low-current resistance associated with the domain wall motion. We suggest the finite slope of Shapiro steps as the characteristic feature of the regime with domain wall oscillations…
Controlling magnetism through Ising superconductivity in magnetic van der Waals heterostructures
2022
Van der Waals heterostructures have risen as a tunable platform to combine different electronic orders, due to the flexibility in stacking different materials with competing symmetry broken states. Among them, van der Waals ferromagnets such as CrI3 and superconductors as NbSe2 provide a natural platform to engineer novel phenomena at ferromagnet-superconductor interfaces. In particular, NbSe2 is well known for hosting strong spin-orbit coupling effects that influence the properties of the superconducting state. Here we put forward a ferromagnet/NbSe2/ferromagnet heterostructure where the interplay between Ising superconductivity in NbSe2 and magnetism controls the magnetic alignment of the…
Current Rectification in Junctions with Spin-Split Superconductors
2022
Spin-split superconductors exhibit an electron-hole asymmetric spin-resolved density of states, but the symmetry is restored upon averaging over spin. On the other hand, asymmetry appears again in tunneling junctions of spin-split superconductors with a spin-polarized barrier. As demonstrated recently in both theory and experiment, this fact leads to a particularly strong thermoelectric effect in superconductor-ferromagnet structures. In this work we show another important effect stemming from the electron-hole asymmetry: current rectification. We calculate the charge current in spin-polarized tunnel junctions of a normal metal and a spin-split superconductor with ac and dc voltage bias. In…
Development of an Inductive NIS Thermometer
2012
We have studied an inductive readout for normal metal-insulator-superconductor (NIS) tunnel junctions by using on-chip planar inductors and a DC SQUID (superconducting quantum interference device) to develop a sensitive and fast thermometer for studies of nanoscale heat conduction and bolometry. Our initial results show the feasibility of the concept, with a good sensitivity for temperatures below 1 K for aluminum as the superconductor when voltage biased close to the superconductor energy gap. peerReviewed
Patterning of Suitable Structures for the Investigation of the Josephson Effect in YBa2Cu3O7/PrBa2Cu3O7 Superlattices
1996
The aim of our work is to investigate the Josephson effect in YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ superlattices. In the case of current flow along c axis direction the superlattice forms an array of artificial Josephson junctions where the YBa 2 Cu 3 O 7-δ layers are the superconducting electrodes which are separated but Josephson coupled by the PrBa 2 Cu 3 O 7-δ sheets. In this paper we report on the preparation, characterisation and patterning of the superlattices into suitable structures via standard photolithograpy and lift-off technique.
Coulomb Blockade and Bloch Oscillations in Superconducting Ti Nanowires
2012
Quantum fluctuations in quasi-one-dimensional superconducting channels leading to spontaneous changes of the phase of the order parameter by $2\pi$, alternatively called quantum phase slips (QPS), manifest themselves as the finite resistance well below the critical temperature of thin superconducting nanowires and the suppression of persistent currents in tiny superconducting nanorings. Here we report the experimental evidence that in a current-biased superconducting nanowire the same QPS process is responsible for the insulating state -- the Coulomb blockade. When exposed to RF radiation, the internal Bloch oscillations can be synchronized with the external RF drive leading to formation of…