اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدGate-controlled spin-orbit interaction in a parabolic GaAs/AlGaAs quantum well
228
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We study the tunability of the spin-orbit interaction in a two-dimensional electron gas with a front and a back gate electrode by monitoring the spin precession frequency of drifting electrons using time-resolved Kerr rotation. The Rashba spin splitting can be tuned by the gate biases, while we find a small Dresselhaus splitting that depends only weakly on the gating. We determine the absolute values and signs of the two components and show that for zero Rashba spin splitting the anisotropy of the spin-dephasing rate vanishes.
قيم البحث
اقرأ أيضاً
In layered semiconductors with spin-orbit interaction (SOI) a persistent spin helix (PSH) state with suppressed spin relaxation is expected if the strengths of the Rashba and Dresselhaus SOI terms, alpha and beta, are equal. Here we demonstrate gate
control and detection of the PSH in two-dimensional electron systems with strong SOI including terms cubic in momentum. We consider strain-free InGaAs/InAlAs quantum wells and first determine alpha/beta ~ 1 for non-gated structures by measuring the spin-galvanic and circular photogalvanic effects. Upon gate tuning the Rashba SOI strength in a complementary magneto-transport experiment, we then monitor the complete crossover from weak antilocalization via weak localization to weak antilocalization, where the emergence of weak localization reflects a PSH type state. A corresponding numerical analysis reveals that such a PSH type state indeed prevails even in presence of strong cubic SOI, however no longer at alpha = beta.
Spin-orbit interaction is investigated in a dual gated InAs/GaSb quantum well. Using an electric field the quantum well can be tuned between a single carrier regime with exclusively electrons as carriers and a two-carriers regime where electrons and
holes coexist. Spin-orbit interaction in both regimes manifests itself as a beating in the Shubnikov-de Haas oscillations. In the single carrier regime the linear Dresselhaus strength is characterized by $beta =$ 28.5 meV$AA$ and the Rashba coefficient $alpha$ is tuned from 75 to 53 meV$AA$ by changing the electric field. In the two-carriers regime the spin splitting shows a nonmonotonic behavior with gate voltage, which is consistent with our band structure calculations.
We report the preparation and readout of multielectron high-spin states, a three-electron quartet, and a four-electron quintet, in a gate-defined GaAs/AlGaAs single quantum dot using spin filtering by quantum Hall edge states coupled to the dot. The
readout scheme consists of mapping from multielectron to two-electron spin states and a subsequent two-electron spin readout, thus obviating the need to resolve dense multielectron energy levels. Using this technique, we measure the relaxations of the high-spin states and find them to be an order of magnitude faster than those of low-spin states. Numerical calculations of spin relaxation rates using the exact diagonalization method agree with the experiment. The technique developed here offers a new tool for the study and application of high-spin states in quantum dots.
We present a computer simulation of exciton-exciton scattering in a quantum well. Specifically, we use quantum Monte Carlo techniques to study the bound and continuum states of two excitons in a 10 nm wide GaAs/Al$_{0.3}$Ga$_{0.7}$As quantum well. Fr
om these bound and continuum states we extract the momentum-dependent phase shifts for s-wave scattering. A surprising finding of this work is that a commonly studied effective-mass mode for excitons in a 10 nm quantum well actually supports two bound biexciton states. The second, weakly bound state may dramatically enhance exciton-exciton interactions. We also fit our results to a hard-disk model and indicate directions for future work.
We carry out microphotoluminescence measurements of an acceptor-bound exciton (A^0X) recombination in the applied magnetic field with a single impurity resolution. In order to describe the obtained spectra we develop a theoretical model taking into a
ccount a quantum well (QW) confinement, an electron-hole and hole-hole exchange interaction. By means of fitting the measured data with the model we are able to study the fine structure of individual acceptors inside the QW. The good agreement between our experiments and the model indicates that we observe single acceptors in a pure two-dimensional environment whose states are unstrained in the QW plain.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
