Acting as artificial synapses, two-terminal memristive devices are considered fundamental building blocks for the realization of neural networks. Organized into large arrays with a top-down approach, in conventional crossbar architecture demonstrated implementation brain-inspired computing supervised and unsupervised learning. Alternative way using unconventional systems consisting many interacting nano-parts have been proposed biologically plausible architectures where emergent behavior...

Superconducting and normal state properties of Niobium nanofilms have been systematically investigated as a function film thickness, on different substrates. The width the superconducting-to-normal transition for all films is remarkably narrow, confirming their high quality. superconducting critical current density exhibits pronounced maximum thickness around 25 nm, marking 3D-to-2D crossover. magnetic penetration depth shows sizeable enhancement thinnest films. Additional amplification...

We present an ultra high sensitive three-dimensional nano Superconducting QUantum Interference Device (nanoSQUID) fabricated by using the Focused Ion Beam sculpting technique. Based on a fully niobium technology, nanodevice consists in superconducting loop (0.2 μm2) interrupted two nanometric Nb/Al-AlOx/Nb Josephson junctions. The nanoSQUID exhibited intrinsic magnetic flux noise as low 0.65 μΦ0/Hz1/2 corresponding to spin less than 10 Bohr magnetons per unit of bandwidth. It has been...

In this work, Milano et al. reported on quantum conductance effects in memristive nanowires, unveiling the origin of deviations levels from integer multiples and analyzing fluctuations over time devices.

Abstract We report on the characterization of NbTi films at $$\sim$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>∼</mml:mo> </mml:math> 11 GHz and in DC magnetic fields up to 4 T, performed by means coplanar waveguide resonator technique, providing quantitative information about penetration depth, complex impedance, vortex-motion-induced resistivity. This kind is essential for development radiofrequency cavity technology. To access vortex-pinning parameters, impedance...

Binary-divided 1 V arrays were fabricated for programmable Josephson voltage standards in close cooperation between INRIM and PTB. The arrays, consisting of 8192 overdamped Nb/Al–AlOxNb SNIS junctions, successfully operated at microwave frequencies around 70 GHz. While the characteristic junctions ranged from 0.25 to 0.6 mV, current margins larger than mA Shapiro step n = 1. In addition, flat steps higher order (n 3 4) generated increased power levels due large voltage, demonstrating small...

We report low-temperature measurements of current–voltage characteristics for highly conductive Nb/Al–AlOx–Nb junctions with thicknesses the Al interlayer ranging from 40 to 150 nm and ultrathin barriers formed by diffusive oxidation surface. In a superconducting state these devices have revealed strong subgap current leakage. Analyzing Cooper-pair quasiparticle currents across devices, we conclude that suppression resistance compared conventional tunnel is not related technologically...

Conventional Josephson metal-insulator-metal devices are inherently underdamped and exhibit hysteretic current-voltage response due to a very high subgap resistance compared that in the normal state. At same time, overdamped junctions with single-valued characteristics needed for most superconducting digital applications. The usual way overcome behavior is place an external low-resistance normal-metal shunt parallel each junction. Unfortunately, such solution results considerable...

The metal assisted etching mechanism for Si nanowire fabrication, triggered by doping type and level coupled with choice of catalyst, is still very poorly understood. We explain the different rates porosities wires we observe based on extensive experimental data, using a new empirical model have developed. establish as key parameter, tunneling through space charge region (SCR) which result reduction SCR width wafer in presence opposite biases p- n-type wafers. This improved understanding...

Following the ever-rising demand for new functionalities and novel materials in superconducting circuitry, we provide a complete view on self-shunting problem Josephson junctions, relating it to specific features of multichannel weak link between electrodes where averaging over channels yields bimodal distribution transparencies with maxima near unity zero. We two examples such internally shunted devices, namely, four-layered Nb/Al-Al oxide-Nb junctions strongly disordered nanometer-thick...

The measurements of dc Josephson and quasiparticle current-voltage characteristics four-layered Nb/Al–AlOx–Nb devices with a fixed Nb thickness 270 nm Al thicknesses ranging from 40 to 120 are reported analyzed in the framework microscopic model developed determine stationary properties dirty limit double-barrier junctions. It is shown that temperature dependence supercurrent as well values characteristic voltages reproduced by calculations only one fitting parameter. We have revealed...

We report the observation of a structurally induced doping compensation mechanism in doped semiconductor nanowires that results from reduced size geometry. This kind can significantly affect electronic transport properties nanowires. demonstrate crystalline n-type Ge wire, compensated by acceptor-like localized surface states, strong electron-electron interactions occur. Variable range hopping conduction detected these is directly generated interactions, exhibiting an unusual large Coulomb...

Abstract Memristive devices that rely on redox-based resistive switching mechanism have attracted great attention for the development of next-generation memory and computing architectures. However, a detailed understanding relationship between involved materials, interfaces, device functionalities still represents challenge. In this work, we analyse effect electrode metals NbO x -based memristive cells. For purpose, Au, Pt, Ir, TiN, Nb top electrodes was investigated in based amorphous grown...

The temperature dependence of the quantized voltage steps near superconducting transition Nb∕Al–AlOx∕Nb overdamped Josephson junctions irradiated at 75GHz has been studied. These can switch between hysteretic and nonhysteretic regime either by varying a fabrication parameter or, as shown in present paper, changing junction operating temperature. Due to high values JC VC up 75kA∕cm2 0.5mV 4.2K, respectively, moderate these parameters, height first rf-induced step was larger than 1mA T=6–8K,...

Niobium-based junctions are still the best candidates for many small-scale applications of superconductivity and in particular, design fabrication programmable voltage standards D/A converters fundamental accuracy. Non-hysteretic with a large current density J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> , reasonable characteristic Vc required, while, order to make these circuits available wider market, operation at temperatures above...

Overdamped Josephson junctions based on a Nb/Al-AlO <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> /Nb superconductor-normal metal-insulator-superconductor structure were realized at the submicrometer scale by using focused ion beam nano-sculpting technique. This approach represents an alternative solution to classical electron lithography and allows for accurate control of junction dimensions. Superconductor-normal structured downscaled...

We describe the first use of a novel photoresist-free X-ray nanopatterning technique to fabricate an electronic device. have produced proof-of-concept device consisting few Josephson junctions by irradiating microcrystals Bi2Sr2CaCu2O8+δ (Bi-2212) superconducting oxide with 17.6 keV synchrotron nanobeam. Fully functional devices been obtained locally turning material into nonsuperconducting state means hard exposure. Nano-XRD patterns reveal that crystallinity is substantially preserved in...

Memristive devices relying on redox-based resistive switching mechanisms represent promising candidates for the development of novel computing paradigms beyond von Neumann architecture. Recent advancements in understanding physicochemical phenomena underlying have shed new light importance an appropriate selection material properties required to optimize performance devices. However, despite great attention has been devoted unveiling role doping concentration, impurity type, adsorbed...

Superconducting nanofilms are tunable systems that can host a 3D–2D dimensional crossover leading to the Berezinskii–Kosterlitz–Thouless (BKT) superconducting transition approaching 2D regime. Reducing dimensionality further, from quasi-1D nanostructures with disorder, generate quantum and thermal phase slips (PS) of order parameter. Both BKT PS complex phase-fluctuation phenomena difficult experiments. We characterized NbN thinner than 15 nm, on different substrates, by...

The temperature stability is one of the most important factors determining successful application Josephson effect to ac voltage standard or analog and digital electronics. Whereas SIS hysteretic junctions with an Ambegaokar-Baratoff (A&B) I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> (T) behavior exhibit a reduced drift around working liquid helium, metallic-barrier SNS follow Kulik-Omelianchuck (K&O) sharp dependence Ic in this...

We report the performance of a reliable three-dimensional nanometer-sized Superconducting QUantum Interference Device (SQUID). The use superconductor-isolator-superconductor Nb/Al-AlOx/Nb Josephson tunnel junctions together with small SQUID loop dimensions permits high modulation depth SQUID's critical current and thus leads to very low intrinsic flux noise device. In particular, we present electrical characterization including detailed investigations. At 4.2 K, two-stage measurements as...

We present here an innovative photon detector based on the proximity junction array device (PAD) working at long wavelengths. show that vortex dynamics in PAD undergoes a transition from Mott insulator to metal state by application of external magnetic field. The also evidences Josephson I-V characteristic with field dependent tunneling current. At high applied currents, we observe dissipative regime which is dominated quasi-particle contribution normal metal. has relatively photo-response...