We study theoretically the effect of spin-orbit coupling on quantum well excitons in a strong magnetic field. We show that, in the presence of an in-plane field component, the excitonic absorption spectrum develops a double-peak structure due to hybridization of bright and dark magnetoexcitons. If the Rashba and Dresselhaus spin-orbit constants are comparable, the magnitude of splitting can be tuned in a wide interval by varying the azimuthal angle of the in-plane field. We also show that the interplay between spin-orbit and Coulomb interactions leads to an anisotropy of exciton energy dispersion in the momentum plane. The results suggest a way for direct optical measurements of spin-orbit parameters.
Anisotropic two-dimensional magnetoexciton with exact center-of-mass separation
Ho Chi Minh City University of Education（胡志明市师范大学）；University of South Florida（南佛罗里达大学）；Thu Dau Mot University（Thu Dau Mot 大学）；University of Architecture Ho Chi Minh City（胡志明市建筑大学）
A spin current through a ferromagnet/heavy-metal interface may shrink due to the spin-flip at the interface, resulting in the spin-memory loss. Here we propose a mechanism of the spin-memory loss. In contrast to other mechanisms based on interfacial spin-orbit coupling, our mechanism is based on the bulk spin-orbit coupling in a heavy-metal. We demonstrate that the bulk spin-orbit coupling induces the entanglement between the spin and orbital degrees of freedom and this spin-orbital entanglement can give rise to sizable spin-flip at the interface even when the interfacial spin-orbit coupling i…
Large spin relaxation anisotropy and valley-Zeeman spin-orbit coupling in WSe2/Gr/hBN heterostructures
大的自旋-轨道邻近效应已经在与过渡金属二硫属化物层界面的石墨烯中被预测。尽管在大载流子密度下发现了增强的自旋轨道耦合的明确证据，但自旋轨道耦合的类型及其弛豫机制仍然未知。我们第一次表明，增加自旋轨道耦合接近石墨烯中的电荷中性点，拓扑状态预计会出现。发现封装在过渡金属二硫属化物WSe $_2$和hBN之间的单层石墨烯表现出优异的质量，迁移率高达100000 cm ^2/V/s。同时，明显的弱反局域化表明了强的自旋-轨道耦合，并发现了由于对称自旋-轨道耦合的存在而导致的大的自旋弛豫各向异性，掺杂相关的测量表明面内自旋的自旋弛豫主要由valley-Zeeman自旋-轨道耦合控制，而内禀自旋-轨道耦合在自旋弛豫中起次要作用.强自旋-谷耦合为探索石墨烯中的自旋和谷自由度提供了新的可能性，实现了自旋操纵的新概念。
The Rashba and Dresselhaus types of spin-orbit coupling are two typical linear coupling forms. We establish the fundamental physics of a model which can be viewed as the double version of the Rashba and Dresselhaus spin-orbit coupling. This model describes the low energy physics of a class of massless Dirac fermions in spin-orbit systems. The physical properties of the massless Dirac fermions are determined by the mathematical relations of spin-orbit coefficients. For equal Rashba and Dresselhauss coupling constants, k-independent eigenspinors and a persistent spin helix combined with massless…
We study the effects caused by Rashba and Dresselhaus spin-orbit coupling over the thermoelectric transport properties of a single-electron transistor, viz., a quantum dot connected to one-dimensional leads. Using linear response theory and employing the numerical renormalization group method, we calculate the thermopower, electrical and thermal conductances, dimensionless thermoelectric figure of merit, and study the Wiedemann-Franz law, showing their temperature maps. Our results for all those properties indicate that spin-orbit coupling drives the system into the Kondo regime. We show that …
By means the envelope function approximation, 8-band Kane model and a finite-difference scheme with the coordinate space discretization, we numerically performed calculations of the spin-orbit coupling parameters for 2D electron gas confined in both symmetric and asymmetric [0 0 1] quantum wells based on zinc-blende III-V semiconductors. Influence of the quantum well band parameters and width as well as the magnitude of the external electric field applied along the growth direction on the Dresselhaus and Rashba spin-orbit coupling parameters is investigated. It has been found that in the symme…
We study the AC field induced current peaks of a spin blockaded double quantum dot with spin-orbit interaction. The AC field modulates either the interdot tunnel coupling or the energy detuning, and we choose the AC field frequency range to induce two singlet-triplet transitions giving rise to two current peaks. We show that for a large detuning the two current peaks can be significantly stronger when the AC field modulates the tunnel coupling, thus making the detection of the spin-orbit gap more efficient. We also demonstrate the importance of the time dependence of the spin-orbit interaction…
We theoretically investigate the nonlinear response of bent graphene, in the presence of artificially-enhanced spin-orbit coupling, which can occur either via adatom deposition, or by placing the sheet of bent graphene in contact with a spin-orbit active substrate. We discuss the interplay between the spin-orbit coupling and the artificial magnetic field generated by the bending, for both the cases of Rashba and intrinsic spin-orbit coupling. For the latter, we introduce a spin-field interaction Hamiltonian addressing directly the electron spin as a degree of freedom. Our findings reveal that …
