We describe how a spin filter may be realized in open quantum-dot systems, by exploiting the Fano resonances that occur their transmission characteristics. In quantum dots which degeneracy of carriers is lifted, we show used as an effective means to generate polarization transmitted carriers, and electrical detection resulting should also possible.

We determine the phase-breaking time ${\mathrm{\ensuremath{\tau}}}_{\mathrm{\ensuremath{\varphi}}}$ of electrons in ballistic quantum dots, from aperiodic fluctuations observed their low-temperature magnetoconductance. Our analysis shows that at temperatures close to a degree Kelvin scales roughly inversely with temperature, reminiscent electron-electron scattering two-dimensional disordered systems. At much lower temperatures, however, saturation is observed, transition between two regimes...

Integer quantum Hall edge states have been imaged in the constriction region of a point contact fabricated an InGaAs heterostructure at high magnetic fields using low-temperature scanning gate microscopy (SGM). Features SGM images grew wider and deeper as side gates squeezed constriction. Furthermore, clear plateaus corresponding to depopulation were observed. We propose model for these based on variation local confinement potential induced by tip.

Using an approach that allows us to probe the electronic structure of strongly pinched-off quantum point contacts (QPCs), we provide evidence for formation self-consistently realized bound states (BSs) in these structures. Our exploits resonant interaction between closely coupled QPCs, and demonstrates BSs may give rise a robust confinement single spins, which show clear Zeeman splitting magnetic field.

We use scanning gate microscopy to probe the ballistic motion of electrons within an open GaAs/AlGaAs quantum dot. Conductance maps are recorded by a biased tip over dot while magnetic field is applied. show that, for specific fields, measured conductance images resemble classical transmitted and backscattered trajectories their mechanical analogue. In addition, we prove experimentally, with this direct measurement technique, existence pointer states. The demonstrated imaging technique...

We investigate electron interference in strongly confined GaAs/AlGaAs quantum dots, by studying the reproducible fluctuations their low-temperature magneto-resistance. Spectral analysis of reveals a strong fundamental peak with well-defined harmonics, suggesting that transport can be dominated remnants just single classical orbit. The orbit is found to relatively insensitive changes gate voltage or temperature, and its existence also suggested numerical simulations devices. Our results...

We study the transport in a system of coupled quantum wires and show evidence for resonant interaction that occurs whenever one them is biased close to pinch off. Measuring conductance wires, as width other varied, we observe peak correlated point at which wire pinches The origin this remains undetermined present, although its characteristics appear consistent with predictions many-body state should form narrow their vanishes.

ESR linewidth, electronic g-value and spin susceptibility of n-type silicon doped with phosphorus arsenic are investigated at temperatures between 1.2 300 K near a metal-nonmetal transition. Temperature, impurity concentration, donor dependences the linewidths discussed regard to relaxation mechanism in line-narrowing low temperatures. ESR-Linienbreite, elektronischer g-Faktor und ESR-Spin-Suszeptibilität von Phosphorund Arsen-dotiertem n-Silizium werden im Temperaturbereich 1,2 bis der Nähe...

We show a dramatic deviation from ergodicity for the conductance fluctuations in graphene. In marked contrast to of dirty metals, generated by varying magnetic field are shown be much smaller than those obtained when sweeping Fermi energy. They also exhibit strongly anisotropic response symmetry-breaking effects field, applied perpendicular or parallel graphene plane. These results reveal complex picture quantum interference graphene, whose description appears more challenging conventional...

When you separate two localized quantum states of electrons spatially, expect their interaction to become weaker. Connecting such with an electron gas in a mesoscopic electronic-transport device, deft experiment, supported by theoretical modeling, shows that the opposite happens.

We investigate energy relaxation of hot carriers in monolayer and bilayer graphene devices, demonstrating that the rate increases significantly as Dirac point is approached from either conduction or valence band. This counterintuitive behavior appears consistent with ideas charge puddling under disorder, suggesting it becomes very difficult to excite out these localized regions. These results therefore demonstrate how peculiar properties extend also its nonequilibrium carriers.

We show a striking transition in the line shape of weak localization peak, observed low-temperature magnetoresistance square semiconductor billiards. More specifically, as point-contact openings to dots are closed, is found develop non-Lorentzian dependence. In smaller dot studied, this can be clearly described linear and within framework current theory behavior only explained terms transition, from chaotic regular scattering dot. Appealing results self-consistent potential-profile...

We report on detailed studies of the low-field magnetoconductance fluctuations observed in ballistic GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As quantum dots. The main finding our study is that temperature-dependent scaling very different from disordered systems. In particular, amplitude decays exponentially with increasing temperature while correlation field remains unaltered. suggest these results are consistent scattering electrons via...

Quasi-periodic conductance fluctuations are observed in the low-temperature magneto-conductance of a bilayer graphene sample. The quasi-periodic nature is confirmed by their Fourier power spectrum, which consists just small number dominant frequency components. From an experimental study these features, highly reminiscent those reported previously for ballistic semiconductor quantum dots, we suggest that they associated with formation open dot submicron

Bound-state (BS) formation in quantum point contacts (QPCs) may offer a convenient way to localize and probe single spins. In this Rapid Communication, we investigate how such BSs are affected by monitoring them with second QPC, which is coupled the BS via wave-function overlap. We show that coupling leads unique detector backaction, weakened increasing its proximity detector. also show, however, interaction between QPCs can be regulated at will using an additional gate control their

We study the influence of finite magnetic field and temperature on spectral characteristics aperiodic fluctuations, observed in magnetoresistance GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As ballistic quantum dots. At temperatures well below 1 K, at sufficiently low fields, fluctuations obscure any average features magnetoresistance. As is increased, such that cyclotron orbit size becomes much smaller than dot dimensions, however, a strong decay...

Electron-spin resonance (ESR) and dc-susceptibility are measured for ${\mathrm{GdBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{y}}$ compounds. From the Curie-Weiss susceptibility frequency dependence of linewidth, we determine Gd dipolar fields about 3 kOe exchange 9 in this system. In order to make origin clear, ESR measurements also performed Ni-doped The linewidths N\'eel temperature depend on Ni concentrations. field compounds is discussed basis results obtained.

The details of electron interference in open quantum-dot arrays are studied experiment and numerical simulations. Reproducible fluctuations observed their low-temperature magnetoconductance the characteristics these suggested to be consistent with a transition from multiple single-dot interference, which occurs as strength interdot coupling is varied. These results therefore reveal nontrivial scaling conductance arrays, thought arise due influence on energy hybridization.

We explore how the transmission properties of a two-dimensional electron gas can be modified by manipulating fringing magnetic fields that emanate from set patterned gates, deposited on top surface its heterojunction. propose multigate device whose conductance is shown to depend sensitively upon relative magnetization and which may therefore use as planar magnetoresistance device, or memory structure.

Focused ion beam (FIB) processes have been developed for Y–Ba–Cu–O superconductor films. A Y–Cu liquid metal source has fabricated, using a Y67 –Cu33 eutectic alloy as the source. As-sputtered film etch rate ratios to GaAs(100) and Si(100) substrates are 0.28 1.4 130-keV Au+ FIB etching, respectively. submicron patterns demonstrated by lithography Cl2 reactive etching. Moreover, superconducting line with 4-μm linewidth fabricated annealing an as-sputtered pattern. Tc control of achieved...

Through a combination of experiment and theory we establish the possibility achieving strong tuning Fano resonances (FRs), by allowing their usual two-path geometry to interfere with an additional, 'intruder', continuum. As coupling strength this intruder is varied, predict modulations resonance line shape that, in principle at least, may exceed amplitude original FR itself. For proof-of-concept demonstration phenomenon, construct nanoscale interferometer from nonlocally coupled quantum...

When a C60 film is irradiated with 3-kV electron-beam (EB), peanut-shaped polymer metallic properties formed. Valence photoelectron spectra of the indicated that density-of-states (DOS) clearly comes across Fermi edge in manner similar to Au used as reference. Interestingly, spectral function around resembles quasi one-dimensional (1D) materials such K0.3MO3 its phase. This suggests has also 1D structure and may exhibit Peierls transition at given temperature. If shows metal-insulator...

We observe periodic oscillations in the weak magnetic-field magnetoresistance for quantum wires subjected to a corrugated gate. This enhanced is attributed backscattering of electrons from gate corrugations due direct ballistic trajectories through multiple (open) dot structures. Simulations transport also show evidence magnetoresistance, suggesting that classical are carried into behavior wire.