Pure spin polarized transport based on Rashba spin orbit interaction through the Aharonov Bohm interferometer embodied four-quantum-dot ring

The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local Rashba spin–orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device.

Thermopower in parallel double quantum dots with Rashba spin-orbit interaction

Based on the Green＇s function technique and the equation of motion approach, this paper theoretically studies the thermoelectric effect in parallel coupled double quantum dots （DQDs）, in which Rashba spin-orbit interaction is taken into account. Rashba spin^rbit interaction contributions, even in a magnetic field, are exhibited obviously in the double quantum dots system for the thermoelectric effect. The periodic oscillation of thermopower can be controlled by tunning the Rashba spin^rbit interaction induced phase. The interesting spin-dependent thermoelectric effects will arise which has important influence on thermoelectric properties of the studied system.

Spin and valley half metal induced by staggered potential and magnetization in silicene

We investigate the electron transport in silicene with both staggered electric potential and magnetization; the latter comes from the magnetic proximity effect by depositing silicene on a magnetic insulator. It is shown that the silicene could be a spin and valley half metal under appropriate parameters when the spin–orbit interaction is considered; further, the filtered spin and valley could be controlled by modulating the staggered potential or magnetization. It is also found that in the spin-valve structure of silicene, not only can the antiparallel magnetization configuration significantly reduce the valve-structure conductance, but the reversing staggered electric potential can cause a high-performance magnetoresistance due to the spin and valley blocking effects. Our findings show that the silicene might be an ideal basis for the spin and valley filter analyzer devices.

Magnetic quantum oscillations in a monolayer graphene under a perpendicular magnetic field

The de Haas van Alphen （dHvA） oscillations of electronic magnetization m a monotayer grapnene with structuteinduced spin orbit interaction （SOI） are studied. The results show that the dHvA oscillating centre in this system deviates from the well known （zero） value in a conventional two-dimensional electron gas. The inclusion of S0I will change the well-defined sawtooth pattern of magnetic quantum oscillations and result in a beating pattern. In addition, the SOI effects ola Hall conductance and magnetic susceptibility are also discussed.

Quantum transport through a Z-shaped silicene nanoribbon

In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are investigated.The calculations are based on the tight-binding model and Green＇s function method in Landauer-Biittiker formalism,in which the electronic density of states（DOS）,transmission probability,and current-voltage characteristics of the system are calculated,numerically.It is shown that the geometry of the ZsSiNR structure can play an important role to control the electron transport through the system.It is observed that the intensity of electron localization at the edges of the ZsSiNR decreases with the increase of the spin-orbit interaction（SOI） strength.Also,the semiconductor to metallic transition occurs by increasing the SOI strength.The present theoretical results may be useful to design silicene-based devices in nanoelectronics.

Thermodynamic behaviour of Rashba quantum dot in the presence of magnetic field

The thermodynamic properties of an In Sb quantum dot have been investigated in the presence of Rashba spin–orbit interaction and a static magnetic field. The energy spectrum and wave-functions for the system are obtained by solving the Schrodinger wave-equation analytically. These energy levels are employed to calculate the specific heat, entropy,magnetization and susceptibility of the quantum dot system using canonical formalism. It is observed that the system is susceptible to maximum heat absorption at a particular value of magnetic field which depends on the Rashba coupling parameter as well as the temperature. The variation of specific heat shows a Schottky-like anomaly in the low temperature limit and rapidly converges to the value of 2kB with the further increase in temperature. The entropy of the quantum dot is found to be inversely proportional to the magnetic field but has a direct variation with temperature. The substantial effect of Rashba spin–orbit interaction on the magnetic properties of quantum dot is observed at low values of magnetic field and temperature.

Topological phase in one-dimensional Rashba wire

We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap.

Analysis and Efficient Solution of Stationary Schrodinger Equation Governing Electronic States of Quantum Dots and Rings in Magnetic Field

In this work the one-band effective Hamiltonian governing the electronic states of a quantum dot/ring in a homogenous magnetic field is used to derive a pair/quadruple of nonlinear eigenvalue problems corresponding to different spin orientations and in case of rotational symmetry additionally to quantum number±ℓ.We show,that each of those pair/quadruple of nonlinear problems allows for the minmax characterization of its eigenvalues under certain conditions,which are satisfied for our examples and the common InAs/GaAs heterojunction.Exploiting the minmax property we devise efficient iterative projection methods simultaneously handling the pair/quadruple of nonlinear problems and thereby saving up to 40%of the computational time as compared to the nonlinear Arnoldi method applied to each of the problems separately.

Energy level splitting of a 2D hydrogen atom with Rashba coupling in non-commutative space

We explore the non-commutative(NC)effects on the energy spectrum of a two-dimensional hydrogen atom.We consider a confined particle in a central potential and study the modified energy states of the hydrogen atom in both coordinates and momenta of non-commutativity spaces.By considering the Rashba interaction,we observe that the degeneracy of states can also be removed due to the spin of the particle in the presence of NC space.We obtain the upper bounds for both coordinates and momenta versions of NC parameters by the splitting of the energy levels in the hydrogen atom with Rashba coupling.Finally,we find a connection between the NC parameters and Lorentz violation parameters with the Rashba interaction.