Department of Physics
Researcher:
Dr. Jian Wang, Professor (jianwang@hkusua.hku.hk)
Dr. Bin Wang, Research Associate (benwb@hku.hk)
Project Title:
First principle investigation of transport properties through longitudinal unzipped carbon nanotube based device
Project Description:
Recently, two new methods of fabricating graphene nano-ribbon (GNR) have been developed experimentally with solution-based oxidative process and Ar plasma etching method, respectively, where GNR was realized by unzipping the multi-wall armchair carbon nanotubes (CNTs) along the longitudinal direction. Through adjusting the experimental conditions, a perfect nano-contact junction of CNT-unzipped CNT-GNR was fabricated. The aim of our project is to investigate the transport properties of such longitudinal unzipped CNT based devices with numerical simulation method.
Project Duration:
May 2009 to March 2010
Project Significance:
The transport investigation of CNT and other carbon-based structures, such as GNR, has been an exciting arena for material science and condensed-matter physics. Since the experimental realization of CNT-unzipped CNT-GNR, a qualitative analysis using the tight-binding (TB) model has been given to analyze the conductance of partly unzipped (6,6) CNT. Because the qualitative analysis can not give all the physics, we think a quantitative investigation using first principles method is necessary and important.
Results Achieved:
We carried out a first principle investigation of transport through several longitudinal unzipped CNT based devices. The basic component of our devices is partially unzipped CNT that consists of GNRs and CNTs as leads. When the edges of graphene are saturated by hydrogen atoms, the system has finite magnetic moment and hence the transport is spin polarized. Our results show that as the Fermi energy is varied the system can change from an insulator to a spin down half-metal, an insulator again, and finally a spin up half-metal. Hence a spin filter device can be designed from this kind of systems.
Our investigation has been published in Physical Review B, 81, 045425, 2010.
Remarks on the Use of High Performance Computing Clusters:
The period of numerical realization of this method was more than three months. Most of our numerical calculations of this project were carried out in the HPC power cluster. We thank the help from HPC Clusters.
