Conductance anomaly near the Lifshitz transition in strained bilayer graphene
Conductance anomaly near the Lifshitz transition in strained bilayer graphene
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DOI：
10.1103/physrevb.85.165429
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发表时间：
2012-02
影响因子：
3.7
通讯作者：
D. A. Gradinar;H. Schomerus;V. Fal’ko
中科院分区：
文献类型：
--
作者：
D. A. Gradinar;H. Schomerus;V. Fal’ko
应变定性地改变双层石墨烯的低能带结构，导致在布里渊区的每个角附近出现一对低能狄拉克锥，以及在与应变成比例的能量处出现Lifshitz转变（色散关系中的鞍点）[ Mucha-Kruczynski，Aleiner和Fal'ko Phys. Rev. B 84 041404（2011）]。在这里，我们表明，在附近的Lifshitz转变，弹道n-p和n-p-n结的电导表现出异常：一个非单调的温度和化学势的依赖性，与大小取决于应变张量的主轴的晶体取向。这种效应是不同极性区域之间的结（n-p和n-p-n结）的特征，而相同极性区域之间的结（n-n′和n-n′-n结）没有异常。
Strain qualitatively changes the low-energy band structure of bilayer graphene, leading to the appearance of a pair of low-energy Dirac cones near each corner of the Brillouin zone, and a Lifshitz transition (a saddle point in the dispersion relation) at an energy proportional to the strain [ Mucha-Kruczynski, Aleiner and Fal'ko Phys. Rev. B 84 041404 (2011)]. Here, we show that in the vicinity of the Lifshitz transition, the conductance of a ballistic n-p and n-p-n junction exhibits an anomaly: a nonmonotonic temperature and chemical potential dependence, with the size depending on the crystallographic orientation of the principal axis of the strain tensor. This effect is characteristic for junctions between regions of different polarity (n-p and n-p-n junctions), while there is no anomaly in junctions between regions of the same polarity (n-n′ and n-n′-n junctions).