Quantum spin Hall effect induced by electric field in silicene

We investigate the transport properties in a zigzag silicene nanoribbon in the presence of an external electric field. The staggered sublattice potential and two kinds of Rashba spin-orbit couplings can be induced by the external electric field due to the buckled structure of the silicene. A bulk gap is opened by the staggered potential and gapless edge states appear in the gap by tuning the two kinds of Rashba spin-orbit couplings properly. Furthermore, the gapless edge states are spin-filtered and are insensitive to the non-magnetic disorder. These results prove that the quantum spin Hall effect can be induced by an external electric field in silicene, which may have certain practical significance in applications for future spintronics device.Comment: 4 pages, 5 figure

First-Principles Investigation of Anistropic Hole Mobilities in Organic Semiconductors

We report a simple first-principles-based simulation model (combining quantum mechanics with Marcus−Hush theory) that provides the quantitative structural relationships between angular resolution anisotropic hole mobility and molecular structures and packing. We validate that this model correctly predicts the anisotropic hole mobilities of ruberene, pentacene, tetracene, 5,11-dichlorotetracene (DCT), and hexathiapentacene (HTP), leading to results in good agreement with experiment

Case Study of Teacher Training for Project STEM Course

Educators are paying more attention to students' hands-on ability with critical thinking which has not been emphasized in previous Chinese education system. To fill this gap, there is a need to organize a hands-on workshop to develop teachers’ STEM hands-on skills to promote on high school campus. Therefore, the purposes of this study are: 1. exploring the development status of teachers' hands-on ability after ending the workshop and 2. exploring the effectiveness of the project-based STEM training with interdisciplinary concept content compared with the traditional STEM training. Based on the two-day teacher training of STEM workshop, this paper used Flanders interaction analysis which is an observation technique used to record and analyze the process and impact of teacher-student interaction in the classroom. Through the analysis, we found that the learners were active in this training course, the interaction between teachers and learners was very frequent, and the relationship between them was quite consistent (harmonious). Then we inferred the training effect of the teachers in the training by combining the works or results submitted by the learners after the workshop. The error rate of these exercises or results was low, indicating that peer discussion or group discussion played an important role in the process of practice. Compared with the traditional iFIAS method, it can be found that in the training based on the project-based teaching model, learners' advanced cognitive abilities such as analysis and synthesis were developed, and their knowledge transfer ability was more flexible, which was also a reflection of interdisciplinary ability

Pure spin current in a two-dimensional topological insulator

We predict a mechanism to generate a pure spin current in a two-dimensional topological insulator. As the magnetic impurities exist on one of edges of the two-dimensional topological insulator, a gap is opened in the corresponding gapless edge states but another pair of gapless edge states with opposite spin are still protected by the time-reversal symmetry. So the conductance plateaus with the half-integer values $e^2/h$ can be obtained in the gap induced by magnetic impurities, which means that the pure spin current can be induced in the sample. We also find that the pure spin current is insensitive to weak disorder. The mechanism to generate pure spin currents is generalized for two-dimensional topological insulators.Comment: 5 pages, 6 figure