Controlled charge pumping in an $\mathrm{Al}\mathrm{Ga}\mathrm{As}∕\mathrm{Ga}\mathrm{As}$ gated nanowire by single-parameter modulation is experimentally and theoretically studied. Transfer of integral multiples the elementary per cycle clearly demonstrated. A simple theoretical model shows that such a quantized current can be generated via loading unloading dynamic quasibound state. It demonstrates nonadiabatic blockade unwanted tunnel events obliterate requirement having at least two...

We present a new fabrication method for epitaxial graphene on SiC which enables the growth of ultra-smooth defect- and bilayer-free sheets with an unprecedented reproducibility, necessary prerequisite wafer-scale high quality graphene-based electronic devices. The inherent but unfavorable formation surface terrace steps during temperature sublimation is suppressed by rapid buffer layer stabilizes surface. enhanced nucleation enforced decomposition polymer adsorbates act as carbon source....

We study tunneling magnetothermopower (TMTP) in $\mathrm{CoFeB}/\mathrm{MgO}/\mathrm{CoFeB}$ magnetic tunnel junction nanopillars. Thermal gradients across the junctions are generated by an electric heater line. Thermopower voltages up to a few tens of $\ensuremath{\mu}\mathrm{V}$ between top and bottom contact nanopillars measured which scale linearly with applied heating power hence thermal gradient. The thermopower signal varies $10\text{ }\text{ }\ensuremath{\mu}\mathrm{V}$ upon reversal...

We evidence multiple coherent precessional magnetization reversal in microscopic spin valves. Stable, reversible, and highly efficient switching is triggered by transverse field pulses as short 140 ps with energies down to 15 pJ. At high fields a phase found revealing periodic transitions from nonswitching under variation of pulse parameters. the low limit existence relaxation dominated regime established allowing amplitudes below quasistatic threshold.

We demonstrate a quasiballistic switching of the magnetization in microscopic magnetoresistive memory cell. By means time resolved magnetotransport, we follow large angle precession free layer spin valve cell upon application transverse magnetic field pulses. Stopping pulse after $180\ifmmode^\circ\else\textdegree\fi{}$ rotation leads to reversal with times as short 165 ps. This mode represents fundamental ultrafast limit induced reversal.

The quasiparticle dynamics of the sheet plasmons in epitaxially grown graphene layers on SiC(0001) has been studied systematically as a function temperature, intrinsic defects, influence multilayers and carrier density using electron energy loss spectroscopy with high momentum resolution. opening an inter-band decay channel appears anomalous kink plasmon dispersion which we describe resonance effect formation electron-hole pairs. Due to inevitable strong coupling single particle excitations...

Abstract The quantitative measurement of the magnetization individual magnetic nanoparticles (MNPs) using force microscopy (MFM) is described. Quantitative realized by calibration MFM signal an MNP reference sample with traceably determined magnetization. A resolution moment order 10 −18 m 2 under ambient conditions demonstrated, which presently limited tip's and noise level instrument. scheme can be applied to practically any microscope tip, thus allowing a wide range future applications,...

Vertically aligned gallium nitride (GaN) nanowire (NW) arrays have attracted a lot of attention because their potential for novel devices in the fields optoelectronics and nanoelectronics. In this work, GaN NW been designed fabricated by combining suitable nanomachining processes including dry wet etching. After inductively coupled plasma reactive ion etching, NWs are subsequently treated chemical etching using AZ400K developer (i.e., with an activation energy 0.69 ± 0.02 eV Cr mask) to form...

We report noninvasive single-charge detection of the full probability distribution ${P}_{n}$ initialization a quantum dot with $n$ electrons for rapid decoupling from an electron reservoir. analyze data in context model sequential tunneling pinch-off, which has generic solutions corresponding to two opposing mechanisms. One limit considers ``freeze-out'' adiabatically evolving grand canonical distribution, other one is athermal equivalent solution generalized decay cascade model. identify...

The future redefinition of the international system units in terms natural constants requires a robust, high-precision quantum standard for electrical base unit ampere. However, reliability any single-electron current source generating nominally quantized output I=ef by delivering single electrons with charge e at frequency f is eventually limited stochastic nature underlying mechanical tunneling process. We experimentally explore path to overcome this fundamental limitation serially...

We report on characterizations of single-electron pumps at the highest accuracy level, enabled by improvements small-current measurement technique. With these a new record in measurements is demonstrated: 0.16 µA · A−1 relative combined uncertainty was reached within less than 1 d time. Additionally, robustness tests pump operation sub-ppm level revealed good stability tunable-barrier against variations operating parameters.

This paper investigates a scheme for quantized charge pumping based on single-parameter modulation. The device was realized in an AlGaAs–GaAs gated nanowire. We find remarkable robustness of the regime against variations driving signal, which increases with applied rf power. feature, together its simple configuration, makes this potential module scalable source current.

The sheet plasmon in epitaxially grown graphene layers on SiC(0001) and the influence of surface roughness have been investigated detail by means low-energy electron diffraction (LEED) energy loss spectroscopy (EELS). We show that existence steps or grain boundaries this epitaxial system is a source strong damping, while dispersion rather insensitive to defects. To first order, lifetime plasmons was found be proportional average terrace length wavelength. A possible reason for surprisingly...

We report on high-accuracy measurements of quantized current, sourced by a tunable-barrier single-electron pump at frequencies $f$ up to $1$ GHz. The were performed with new picoammeter instrument, traceable the Josephson and quantum Hall effects. Current quantization according $I=ef$ $e$ elementary charge was confirmed $f=545$ MHz total relative uncertainty 0.2 ppm, improving state art about factor 5. For first time, accuracy possible future current standard based transport experimentally...

We report on electronic transport measurements in rotational square probe configuration combination with scanning tunneling potentiometry of epitaxial graphene monolayers which were fabricated by polymer-assisted sublimation growth SiC substrates. The absence bilayer the ultralow step edges below 0.75 nm scrutinized atomic force microscopy and result a not yet observed resistance isotropy 4H- 6H-SiC(0001) substrates as low 2%. combine microscopic properties nanoscale experiments thereby...

The surface layers of a GaAs/AlGaAs heterostructure are locally oxidized using an atomic force microscope. local anodic oxidation depletes the underlying two-dimensional electron gas leading to formation tunneling barriers. height barriers is determined by measuring thermally activated current. By varying current, barrier heights can be tuned between few meV and more than 100 meV. Using these as elements, side gated single-electron transistor fabricated.

We study single-parameter quantized charge pumping via a semiconductor quantum dot in high magnetic fields. The is defined between two top gates an AlGaAs/GaAs heterostructure. Application of oscillating voltage to one the leads pumped current plateaus gate characteristic, corresponding controlled transfer integer multiples electrons per cycle. In perpendicular-to-plane field become more pronounced indicating improved quantization. Current quantization sustained up fields where full spin...

Abstract The consequences of the revision International System Units for electrical quantum metrology are discussed herein. Possible applications single‐electron transport pump devices and other topical state‐of‐the‐art methodologies based on effects reviewed, with a focus their potential implications in future.

Abstract This paper reports on the direct qualitative and quantitative performance comparisons of field-effect transistors (FETs) based vertical gallium nitride nanowires (GaN NWs) with different NW numbers (i.e., 1–100) diameters 220–640 nm) fabricated same wafer substrate to prove feasibility employing 3D architecture concept towards massively parallel electronic integration, particularly for logic circuitry metrological applications. A top-down approach combining both inductively coupled...

Graphene, the first true two-dimensional material still reveals most remarkable transport properties among growing class of materials. Although many studies have investigated fundamental scattering processes, surprisingly large variation in experimentally determined resistances associated with a localized defect is an open issue. Here, we quantitatively investigate local graphene prepared by polymer assisted sublimation growth (PASG) using scanning tunneling potentiometry. PASG characterized...

This paper reports on the normally off GaN vertical MOSFETs based nanowires (NWs) with an inverted p-GaN channel and a wrap-around-gate structure for first time. Both inductively coupled plasma dry reactive-ion etching wet-chemical were employed to fabricate vertically aligned NWs from epitaxial thin films specified doping profile. During wet etching, influence of p-doping NW morphology was investigated, results could be explained by proposed model. In comparison other c-axis transistors,...

In this study, we first show that the argon flow during epitaxial graphene growth is an important parameter to control quality of buffer and layer. Atomic force microscopy (AFM) low-energy electron diffraction (LEED) measurements reveal decomposition SiC substrate strongly depends on Ar mass rate while pressure temperature are kept constant. Our data interpreted by a model based competition rate, controlled flow, with uniform layer formation under equilibrium process at surface. The proper...

Recent advances in the field of condensed-matter physics have unlocked potential to realize and control emergent material phases that do not exist thermal equilibrium. One most promising concepts this regard is Floquet engineering, coherent dressing matter via time-periodic perturbations. However, broad applicability engineering quantum materials still unclear. For paradigmatic case monolayer graphene, theoretically predicted Floquet-induced effects, despite a seminal report light-induced...