"石墨电子结构和输运特性"专题研讨会简讯

"石墨电子结构和输运特性"专题研讨会于2008年4月11-13日在山东青岛举行,会议由复旦大学物理系,南京大学物理系和青岛大学物理学院联合主办,受到国家自然科学基金委及国家量子调控重大科学研究计划(2006CB921800)资助.     

Detection of Majorana fermions in an Aharonov–Bohm interferometer

By using the non-equilibrium Green's function technique, we investigate the electronic transport properties in an Aharonov–Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak which is independent of the other factors when the topological superconductor is grounded. Especially, an additional phase appears when the topological superconductor is in the strong Coulomb regime, which induces a new conductance resonant peak compared with the structure of replacing the topological superconductor by a quantum dot, and the conductance oscillation with the magnetic flux reveals a 2π phase shift by raising(lowering) a charge on the capacitor.     

Generation and Quantum Interference of Entangled Electron-Hole Pairs in a Hanbury Brown and Twiss Interferometer

The Hanbury Brown-Twiss interferometer is proposed to serve as a detector of the crossed Andreev reflection and to generate entangled electron-hole pairs. It is shown that the non-local electron and hole induced by the crossed Andreev reflection are entangled. Quantum interference of the entangled electron-hole pairs gives rise to a new measurable effect of the phase difference between two superconductors in the cross correlation. The present theoretical predictions can be experimentally realized within the present-day microelectronic technology.     

磁性纳米电机单电子晶体管的自旋输运特性

文章作者在研究磁性隧道结的自旋输运中引入量子点的机械振动自由度,将单电子隧穿和振动自由度耦合所导致的shuttle输运理论应用到自旋电子学中,研究结果表明,shuttle输运对自旋极化输运有很大的影响,其独特的输运性质可以用来设计自旋电子器件,文章在理论上提出具有巨磁效应的自旋阀、高性能的半导体自旋注入器以及电流的整流器.     

All-electric-controlled spin current switching in single-molecule magnet-tunnel junctions

A single-molecule magnet (SMM) coupled to two normal metallic electrodes can both switch spin-up and spin-down electronic currents within two different windows of SMM gate voltage. Such spin current switching in the SMM tunnel junction arises from spin-selected single electron resonant tunneling via the lowest unoccupied molecular orbit of the SMM. Since it is not magnetically controlled but all-electrically controlled,the proposed spin current switching effect may have potential applications in future spintronics.     

Impurity Effects at Surfaces of a Photon-Dressed Bi_2Se_3 Thin Film

We investigate the impurity effects on surfaces of a thin film topological insulator, applied by an off-resonant circular polarized light. It is found that the off-resonant driving induces a quantized total Hall conductivity, when the driving strength is larger than a critical value and the Fermi level lies in the band gap, indicating that our system is converted into the topological phase. We also find that with the increasing disorder strength, the Dirac masses of top and bottom surfaces are renormalized and then fixed to half of their initial values, respectively,which will shrink the widths of the half-integer plateau of anomalous Hall conductivities.