The Transport And Control Of Quantum Spinor States In Silicene Mesoscopic Structures

In recent years,silicene has been experimentally synthesized,and it is a graphene-like two-dimensional material.Besides sharing exotic Dirac fermion physics of graphene,silicene has many attractive properties like field-tunable bandgap,large spin-orbit coupling effects and spin-valley locking.These properties play an important role to research topological quantum states and construct atomically silicon-based photoelectric devices.Based on these particular physics,applying the method of model Hamiltonian,we mainly research the transport and control of quantum spinor states in different silicene mesoscopic structures.For the topic of dwell time,Goos-Hanchen-like shift and quantum dots.We have obtained the following resultsThe evaluation of dwell time in silicene mesoscopic structures.Residing on the gate-tunable electronic properties of silicene,we have systematically examined the dwell time for quantum tunneling through the single and multiple-gated silicene nanostructures.It is shown that unlike the graphene,Hartman effect is observable even at the normal incidence due to the sizeable spin-orbit gap of silicene.Together with its field-tunable bandgap,we show that this Hartman effect can be further flexibly switched on and off via electric mean.By simulating the dwell time through the symmetric and asymmetric double barrier structures,it is also shown here that the dwell time displays the distinct dependence on the former and latter barrier profiles.Those observations provide some favorable strategies to experimentally examine and fundamentally understand the time-dependent aspect of tunneling in solid state nanosystems.Goos-Hanchen-like shift in silicene mesoscopic structures.We have theoretically studied the Goos-Hanchen-like shift of spinor-unpolarized beams tunneling through various gate-biased silicene nanostructures.Following the stationary-phase method,lateral displacement in single-,dual-,and multiple-gated silicene system has been systematically demonstrated.It is shown for simple single-gated silicene lateral displacement can be generally enhanced by Fabry-Perot interference,and near the transition point turning on the evanescent mode very large lateral shift could be observed.For the dual-gated structure,we have also shown the crucial role of localized modes like quantum well states in enhancing the beam lateral displacement,while for the multiple gate-biased systems the resulting superlattice subbands are also favorable for lateral displacement enhancement.Importantly,including the degeneracy-broken mechanisms such as gate-field and magnetic modulations,fully spinor-resolved beam can be distinguished from the rest counterparts by aligning the incident beam with proper spinor-resolved transition point,localized state,and subband,all of which can be flexibly modulated via electric means,offering the very desirable strategies to achieve the fully spinor-polarized beam for functional electronic applications.Silicene quantum dots.We have theoretically studied the localized states of Dirac fermions in a silicene quantum dots with(without)the modulation of magnetic field.For the zero magnetic field case,there are no localized states but form some states of long lifetime by aligning energy with resonant states.Together with its field-tunable bandgap,confined states corresponding to a nonzero magnetic field could be well controlled under the modulation of gate-field and magnetic field.The energy level of confined states as a function of the radius of quantum dots have been also shown and demonstrated between two orbital momenta obvious energy crossing could be observed.Importantly,considering the degeneracy-broken mechanisms under the external magnetic and electric field modulation together,the valley-dependent energy levels of confined states could be observed.These observations could provide some favorable strategies to confine Dirac fermions in silicene-based quantum dots system.