94 research outputs found
Anisotropic Pauli spin-blockade effect and spin-orbit interaction field in an InAs nanowire double quantum dot
We report on experimental detection of the spin-orbit interaction field in an
InAs nanowire double quantum dot device. In the spin blockade regime, leakage
current through the double quantum dot is measured and is used to extract the
effects of spin-orbit interaction and hyperfine interaction on spin state
mixing. At finite magnetic fields, the leakage current arising from the
hyperfine interaction is suppressed and the spin-orbit interaction dominates
spin state mixing. We observe dependence of the leakage current on the applied
magnetic field direction and determine the direction of the spin-orbit
interaction field. We show that the spin-orbit field lies in a direction
perpendicular to the nanowire axis but with a pronounced off-substrate-plane
angle. It is for the first time that such an off-substrate-plane spin-orbit
field in an InAs nanowire has been detected. The results are expected to have
an important implication in employing InAs nanowires to construct spin-orbit
qubits and topological quantum devices.Comment: 20 pages, 5 figures, Supporting Informatio
Gate defined quantum dot realized in a single crystalline InSb nanosheet
Single crystalline InSb nanosheet is an emerging planar semiconductor
material with potential applications in electronics, infrared optoelectronics,
spintronics and topological quantum computing. Here we report on realization of
a quantum dot device from a single crystalline InSb nanosheet grown by
molecular-beam epitaxy. The device is fabricated from the nanosheet on a
Si/SiO2 substrate and the quantum dot confinement is achieved by top gate
technique. Transport measurements show a series of Coulomb diamonds,
demonstrating that the quantum dot is well defined and highly tunable. Tunable,
gate-defined, planar InSb quantum dots offer a renewed platform for developing
semiconductor-based quantum computation technology.Comment: 12 pages, 4 figure
Weak antilocalization and electron-electron interaction in coupled multiple-channel transport in a BiSe thin film
Electron transport properties of a topological insulator BiSe thin
film are studied in Hall-bar geometry. The film with a thickness of 10 nm is
grown by van der Waals epitaxy on fluorophlogopite mica and Hall-bar devices
are fabricated from the as-grown film directly on the mica substrate. Weak
antilocalization and electron-electron interaction effects are observed and
analyzed at low temperatures. The phase-coherence length extracted from the
measured weak antilocalization characteristics shows a strong power-law
increase with decreasing temperature and the transport in the film is shown to
occur via coupled multiple (topological surface and bulk states) channels. The
conductivity of the film shows a logarithmically decrease with decreasing
temperature and thus the electron-electron interaction plays a dominant role in
quantum corrections to the conductivity of the film at low temperatures.Comment: 12 pages, 5 figure
Two-dimensional Mott variable-range hopping transport in a disordered MoS nanoflake
The transport characteristics of a disordered MoS nanoflake in the
insulator regime are studied by electrical and magnetotransport measurements.
The layered MoS nanoflake is exfoliated from a bulk MoS crystal and the
conductance and magnetoresistance are measured in a four-probe setup over a
wide range of temperatures. At high temperatures, we observe that
exhibits a temperature dependence and the transport in the nanoflake
dominantly arises from thermal activation. At low temperatures, where the
transport in the nanoflake dominantly takes place via variable-range hopping
(VRH) processes, we observe that exhibits a
temperature dependence, an evidence for the two-dimensional (2D) Mott VRH
transport. The measured low-field magnetoresistance of the nanoflake in the
insulator regime exhibits a quadratic magnetic field dependence with , fully consistent with the 2D Mott VRH transport
in the nanoflake.Comment: 14 pages, 4 figures, and Supplemental Material
First integrals of the Maxwell–Bloch system
We investigate the analytic, rational and first integrals of the Maxwell–Bloch system
\begin{equation*}
\dot{E}=-\kappa E+gP,\quad \dot{P}=-\gamma _{\bot }P+gE\triangle , \quad \dot{\triangle }=-\gamma _{\Vert }(\triangle -\triangle _0)-4gPE,
\end{equation*}
where are real parameters. In addition, we prove this system is rationally non-integrable in the sense of Bogoyavlenskij for almost all parameter values
First integrals of the Maxwell–Bloch system
We investigate the analytic, rational and first integrals of the Maxwell–Bloch system
\begin{equation*}
\dot{E}=-\kappa E+gP,\quad \dot{P}=-\gamma _{\bot }P+gE\triangle , \quad \dot{\triangle }=-\gamma _{\Vert }(\triangle -\triangle _0)-4gPE,
\end{equation*}
where are real parameters. In addition, we prove this system is rationally non-integrable in the sense of Bogoyavlenskij for almost all parameter values
Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles
doi:10.1063/1.2425010Multilayer reactive electron-beam evaporation of thin aluminum oxide layers with embedded silver nanoparticles (Ag-nps) has been used to create a dielectric thin film with an enhanced permittivity. The results show a frequency dependent increase of the dielectric constant κ. Overall stack κ of the control sample was found to be 7.7-7.4 in the 1 kHz-1 MHz range. This is in comparison with κ = 16.7-13.0 over the same frequency range in the sample with Ag-nps. Capacitance-voltage and conductance-voltage measurements indicate the presence of charge capture resulting from the Ag-nps. The authors attribute this dielectric constant enhancement to dipole and space charge polarization mechanisms.The authors thank M. Othman for ellipsometry measurements. They are also grateful for the funding provided by the National Science Foundation Grant No. ECS0223
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