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.     

硼或氮掺杂的锯齿型石墨烯纳米带的非共线磁序与电子输运性质

基于非共线磁序密度泛函/非平衡格林函数方法,研究了硼或氮掺杂的锯齿型石墨烯纳米带的非共线磁序与电子透射系数.未掺杂的石墨烯纳米带的计算结果表明磁化分布主要遵循类似于Neel磁畴壁的螺旋式磁化分布.相比于未掺杂的情况,硼/氮掺杂的石墨烯纳米带的磁化分布出现了双区域的特征,即杂质原子附近的磁化较小,杂质原子左(右)侧区域的磁化分布更接近于左(右)电极的磁化方向,这为通过掺杂手段在石墨烯纳米带边缘上构建不同磁畴壁提供了可能性.与未掺杂的透射系数不同的是,硼/氮掺杂的石墨烯纳米带的透射系数在费米面附近随着磁化偏转角增大而减小,表明非共线磁序引起的自旋翻转散射占据主导地位.而在E=±0.65 eV处,出现了一个较宽的dip结构,投影电子态密度的分析表明其来源于杂质原子形成的束缚态所引起的背散射.我们的研究结果对于理解石墨烯纳米带中的非共线磁序与杂质散射以及器件设计具有一定的意义.     

Impact of Phosphorus superlattices on charge and spin dependent transport properties of zigzag silicene nanoribbons

To investigate charge and spin dependent conductance properties of Phosphorus doped zigzag silicene nanoribbons (ZSiNRs), we utilize recursive Green's function method and Landauer-Büttiker formalism. Our calculations are performed in the absence and presence of exchange magnetic fields with both parallel and antiparallel configurations. Considering a supperlattice of Phosphorus substituents in a periodic distribution at the edge of nanoribbon, the effect of increasing number of dopants and period of the distribution on transport properties are studied. It is found that transport properties of doped ZSiNRs vary with doping concentration according to being odd or even of number of dopants. For parallel configuration, doped ZSiNR with various concentrations works as a controllable spin filter with Fermi energy. Increasing doping concentration leads to increasing size of conductance gap and improvement of controlling quality of spin-filtering property while increasing period of Phosphorus atomic distribution has destructive effect on size of conductance gap and destroys spin-filtering property. Moreover, we show that although the same results are obtained for transport properties of doped ZSiNR with various concentrations of Phosphorus atoms in presence of antiparallel exchange magnetic fields, a completely controllable spin-filtering property cannot be achieved by Fermi energy changes.     

Defect engineering on the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons

We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons(APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density functional calculations. It is found that the atomic vacancies are easier to form and detain at the edge region rather than a random distribution through analyzing formation energy and diffusion barrier. The highly local defect states are generated at the vicinity of the Fermi level, and emerge a deep-to-shallow transformation as the width increases after introducing vacancies in APNRs.Moreover, the electrical transport of APNRs with vacancies is enhanced compared to that of the perfect counterparts. Our results provide a theoretical guidance for the further research and applications of PNRs through defect engineering.     

The electronic properties and electron transport of sawtooth penta-graphene nanoribbon under uniaxial strain: ab-initio study

ABSTRACT

The electronic properties and electron transport of a sawtooth penta-graphene nanoribbon (SSPGNR) under uniaxial strains are theoretically studied by density-functional theory (DFT) in combination with the non-equilibrium Green's function formalism. We investigated the electronic structures and the current–voltage (I–V) characteristics of the SSPGNRs under a sequence of uniaxial strains in range from 10% compression to 10% stretch. In this strained range, carbon atoms still keep a pentagon network, but with the changing bond lengths. The C–C bond lengths change almost linearly with the tolerable strain. The value of the band gap of SSPGNRs can be depicted as a parabola under uniaxial strain. Our calculations show that the current is monotonous increase with compressive strain at the same applied bias voltage. In case of tensile strain, the variable rule of the current is different that it increases at first and decrease later. The fundamental physical properties (band structure, I–V characteristic) of SSPGNRs seem to be more sensitive to compressive strain than the stretch strain. The current intensity of the compressive-SSPGNR is by 2 orders of magnitude compared to that of the tensile-SSPGNR at the same strain in range from 6% to 10%. The results obtained from our calculations are beneficial to practical applications of these strained structures in SSPGNRs-based electromechanical devices.