Search results for "TUNNEL"

RELAXATION PHENOMENA IN CLASSICAL AND QUANTUM SYSTEMS

2012

Relaxation phenomena in three different classical and quantum systems are investigated. First, the role of multiplicative and additive noise in a classical metastable system is analyzed. The mean lifetime of the metastable state shows a nonmonotonicbehavior with a maximum as a function of both the additive and multiplicative noise intensities. In the second system, the simultaneous action of thermal and non-Gaussian noise on the dynamics of an overdamped point Josephson junction is studied. The effect of a Lévy noise generated by a Cauchy–Lorentz distribution on the mean lifetime of the superconductive metastable state, in the presence of a periodic driving, is investigated. We find resonan…

Measurements of tunneling conduction to carbon nanotubes and its sensitivity to oxygen gas

2012

We have measured the conductive properties of junctions between carbon nanotubes (CNT) and non-noble metals $M$ ($M$ = Al, Ti, Nb), which are separated by the native oxide (${M}_{\mathit{OX}}$) of the metal. Reproducible and asymmetric current-voltage characteristics were obtained from Ti/Ti${}_{\mathit{OX}}$/CNT and Nb/Nb${}_{\mathit{OX}}$/CNT junctions, while Al/Al${}_{\mathit{OX}}$/CNT exhibited no current until breakdown, which is attributed to the larger bandgap of Al${}_{\mathit{OX}}$. The conduction in the Ti- and Nb-based junctions is not due to direct tunneling since they exhibit strong temperature dependence. The presence of oxygen is shown to drastically, but reversibly, modify t…

Incorporation of CrIII into a Keggin Polyoxometalate as a Chemical Strategy to Stabilize a Labile {CrIIIO4} Tetrahedral Conformation and Promote Unat…

2020

Polyoxometalates (POMs) provide rigid and highly symmetric coordination sites and can be used as a strategy for the stabilization of magnetic ions. Herein, we report a new member of the Keggin archetype, the Cr-centered Keggin anion [α-CrW12O40]5– (CrW12), with the unusual tetrahedral coordination of CrIII reported for the first time in POMs conferring unattended magnetic properties. POM chemistry has recently presented excellent examples of single-molecule and single-ion magnets (SMMs and SIMs) as well as molecular spin qubits; however, the majority of POM-based SIMs reported to date contain lanthanoid ions. CrW12, as the first example of a chromium(III) SIM, exhibits slow relaxation of ma…

Analisi del posizionamento dei tunnel ossei nella ricostruzione del legamento crociato anteriore mediante TC e ripresa funzionale nello sportivo.

Atomic-scale magnetic domain walls in quasi-one-dimensional Fe nanostripes.

2001

Fe nanostripes on W(110) are investigated by Kerr magnetometry and spin-polarized scanning tunneling microscopy (SP-STM). An Arrhenius law is observed for the temperature dependent magnetic susceptibility indicating a one-dimensional magnetic behavior. The activation energy for creating antiparallel spin blocks indicates extremely narrow domain walls with a width on a length scale of the lattice constant. This is confirmed by imaging the domain wall by SP-STM. This information allows the quantification of the exchange stiffness and the anisotropy constant.

Moir\'e-enabled topological superconductivity

2020

The search for artificial topological superconductivity has been limited by the stringent conditions required for its emergence. As exemplified by the recent discoveries of various correlated electronic states in twisted van der Waals materials, moir\'e patterns can act as a powerful knob to create artificial electronic structures. Here, we demonstrate that a moir\'e pattern between a van der Waals superconductor and a monolayer ferromagnet creates a periodic potential modulation that enables the realization of a topological superconducting state that would not be accessible in the absence of the moir\'e. The magnetic moir\'e pattern gives rise to Yu-Shiba-Rusinov minibands and periodic mod…

Aerodynamics of an isolated ski jumping ski

2019

A single isolated ski was suspended from a six-component wind tunnel balance and three angles, the angle of attack, the yaw angle and the edge angle were adjustable during the test. Increasing yaw angle from 0 to 15° increased the lift coefficient CL from 0.42 to 0.90 at edge angle 0° and from 0.70 to 0.87 at edge angle 10°, respectively. Increasing yaw angle also increased the sensitivity of the ski to changes in edge angle, i.e., increasing the edge angle (20°–45°) decreased the CL and the ratio $$C_{L}^{2}/{C_D}$$ with large yaw angles. However, to maximize the lift-to-drag ratio with a typical angle of attack of 30° in ski jumping, it may be reasonable to have an edge angle of 5°–10° on…

Disorder-induced gap in the normal density of states of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br

2015

The local density of states (DOS) of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, measured by scanning tunneling spectroscopy on in situ cleaved surfaces, reveals a logarithmic suppression near the Fermi edge persisting above the critical temperature T(c). The experimentally observed suppression of the DOS is in excellent agreement with a soft Hubbard gap as predicted by the Anderson-Hubbard model for systems with disorder. The electronic disorder also explains the diminished coherence peaks of the quasi-particle DOS below T(c).

Tunneling luminescence in long lasting afterglow of SrAl 2 O 4 :Eu,Dy

2017

The publication is prepared with the financial support of National Research Programme IMIS2.

Structure and electronic properties of ultrathin Co films on W(110)

2004

Abstract The structure and electronic properties of ultrathin Co films on W(1 1 0) grown by molecular beam epitaxy in UHV were investigated by low energy electron diffraction (LEED) and scanning tunneling microscopy and spectroscopy (STM and STS). For coverages above 0.7 ML the pseudomorphic (ps) monolayer is transformed gradually into close-packed (cp-) monolayer areas, showing up as separated islands that increase in size with coverage until the cp-monolayer is complete. Two different structures of the cp-monolayer were observed by atomically resolved STM, both leading to a 8 × 1 superstructure in the LEED pattern. Higher coverages continue to grow in the Stransky–Krastanov growth mode fo…