اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدCharge pumping and noise in a one-dimensional wire with weak electron-electron interactions
109
0
0.0
(
0
)
تأليف
Pierre Devillard
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We consider the adiabatic pumping of charge through a mesoscopic one dimensional wire in the presence of electron-electron interactions. A two-delta potential model is used to describe the wire, which allows to obtain exactly the scattering matrix coefficients, which are renormalized by the interactions. Two periodic drives, shifted one from another, are applied at two locations of the wire in order to drive a current through it in the absence of bias. Analytical expressions are obtained for the pumped charge, current noise, and Fano factor in different regimes. This allows to explore pumping for the whole parameter range of pumping strengths. We show that, working close to a resonance is necessary to have a comfortable window of pumping amplitudes where charge quantization is close to the optimum value: a single electron charge is transferred in one cycle. Interactions can improve the situation, the charge $Q$ is closer to one electron charge and noise is reduced, following a $Q (1-Q)$ behavior, reminiscent of the reduction of noise in quantum wires by $T (1-T)$, where $T$ is the energy transmission coefficient. For large pumping amplitudes, this charge vanishes, noise also decreases but slower than the charge.
قيم البحث
اقرأ أيضاً
The combined presence of a Rashba and a Zeeman effect in a ballistic one-dimensional conductor generates a spin pseudogap and the possibility to propagate a beam with well defined spin orientation. Without interactions transmission through a barrier
gives a relatively well polarized beam. Using renormalization group arguments, we examine how electron-electron interactions may affect the transmission coefficient and the polarization of the outgoing beam.
Single crystal ZnO nanowires doped with indium are synthesized via the laser-assisted chemical vapor deposition method. The conductivity of the nanowires is measured at low temperatures in magnetic fields both perpendicular and parallel to the wire a
xes. A quantitative fit of our data is obtained, consistent with the theory of a quasi-one-dimensional metallic system with quantum corrections due to weak localization and electron-electron interactions. The anisotropy of the magneto-conductivity agrees with theory. The two quantum corrections are of approximately equal magnitude with respective temperature dependences of T^-1/3 and T^-1/2. The alternative model of quasi-two-dimensional surface conductivity is excluded by the absence of oscillations in the magneto-conductivity in parallel magnetic fields.
One-dimensional lattice with strong spin-orbit interactions (SOI) and Zeeman magnetic field is shown to lead to the formation of a helical charge-density wave (CDW) state near half-filling. Interplay of the magnetic field, SOI constants and the CDW g
ap seems to support Majorana bound states under appropriate value of the external parameters. Explicit calculation of the quasi-particles wave functions supports a formation of the localized zero-energy state, bounded to the sample end-points. Symmetry classification of the system is provided. Relative value of the density of states shows a precise zero-energy peak at the center of the band in the non-trivial topological regime.
In the integer quantum Hall (IQH) regime, an antidot provides a finite, controllable `edge of quantum Hall fluid that is an ideal laboratory for investigating the collective dynamics of large numbers of interacting electrons. Transport measurements o
f single antidots probe the excitation spectra of the antidot edge, and gate-defined antidot devices offer the flexibility to vary both the antidots dimensions and its couplings to extended IQH edge modes which serve as leads. We also use the spin-selectivity of the IQH edge modes to perform spin-resolved transport measurements, from which we can infer the antidot spin-structure. This thesis describes a combination of such transport experiments and related computational models designed to investigate the effects of electron-electron interactions in quantum antidots, with general implications for the physics of spin and charge in IQH systems.
We use microscopic linear response theory to derive a set of equations that provide a complete description of coupled spin and charge diffusive transport in a two-dimensional electron gas (2DEG) with the Rashba spin-orbit (SO) interaction. These equa
tions capture a number of interrelated effects including spin accumulation and diffusion, Dyakonov-Perel spin relaxation, magnetoelectric, and spin-galvanic effects. They can be used under very general circumstances to model transport experiments in 2DEG systems that involve either electrical or optical spin injection. We comment on the relationship between these equations and the exact spin and charge density operator equations of motion. As an example of the application of our equations, we consider a simple electrical spin injection experiment and show that a voltage will develop between two ferromagnetic contacts if a spin-polarized current is injected into a 2DEG, that depends on the relative magnetization orientation of the contacts. This voltage is present even when the separation between the contacts is larger than the spin diffusion length.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
