扭曲双层石墨烯的层间电导特性研究

Study on the interlayer conductance of twisted bilayer graphene

扭曲双层石墨烯(TBG)由于具有莫特绝缘和非常规超导等新奇的电学特性,在纳米技术领域存在巨大的应用潜力.本文基于光学衍射物理方法,构建了一个适用于TBG的理论模型,并利用该理论模型研究了TBG的层间电导特性.研究结果较好地解释了TBG层间电导随扭转角变化的实验结果,并阐明了其物理机制.此外,本文还计算了电极参数、隧穿层厚度以及界面势强度等物理因素对层间电导特性的影响.计算结果表明:随着电极化学势的增大,层间电导关于扭转角的变化曲线近似整体向上平移;层间电导随着上层隧穿层厚度的增加而衰减并趋于稳定,而随着下层隧穿层厚度振荡;TBG两层扭转石墨烯的界面势强度越强,则层间电导随扭转角下降得越快.

Twisted bilayer graphene(TBG)possesses great potential in the field of nanotechnology due to its novel electrical properties such as tunable Mott insulativity and unconventional superconductivity.Based on the optical diffraction method,we have developed a theoretical model for TBG.By using this theoretical model,the interlayer conductance of TBG is investigated.The theoretical results can well interpret the experimental curve of the interlayer conductance of TBG,and the physical mechanism is clarified.In addition,we have calculated the influences of the electrode parameters,the thickness of the tunneling layer and the strength of interface potential on the interlayer conductance.The numerical results show that,the curve of the interlayer conductance versus twist angle moves upwards with increasing chemical potential of electrodes;the interlayer conductance first decreases and then tends to be independent with the thickness of the upper tunneling layer,while it oscillates with the thickness of the lower tunneling layer;the interlayer conductance decreases more rapidly with the twist angle as the interface potential becomes stronger.