次近邻效应对二维材料特性的影响
The next nearest neighbor effect on the 2D materials properties
摘要：
本文以石墨烯二维蜂窝状二子晶格为例，研究了在二维材料中引入次近邻跳跃的影响。研究发现，在二维材料中引入NNN后，费米能级周围的对称性被消除，并发生了位移，但NNN的跳跃值很小。这种效应随着NNN跳变的增加而增加。如果NNN跳变与最近邻（NN）跳变竞争，则二维材料的色散关系完全从NN跳变色散关系改变。结果表明，二维蜂窝晶格中材料对NNN跳跃效应的敏感性远大于二维正方晶格中材料的敏感性。这是由于NNN位点的数量等于6，这是二维蜂窝晶格中NN位点的两倍。同时，NNN位置的数量等于4，这等于二维正方形晶格中的NN位置。因此，我们的结论是，通过改变NNN和NN网站之间的比例在二维晶格可以调整NNN跳跃效应的灵敏度。
英文摘要：
In this work, the effect of introducing next nearest neighbor (NNN) hopping to the 2D materials was studied using the graphene 2D honeycomb two sublattice as an example. It is found that introducing NNN to the 2D materials removes the symmetry around the Fermi level and shifts it, at a small value of NNN hopping. This effect increases with increasing NNN hopping. If the NNN hopping becomes competitive with nearest neighbor (NN) hopping, the dispersion relations of the 2D materials changes completely from NN hopping dispersion relations. The results show that the 2D material sensitivity for NNN hopping effect is much larger in the 2D honeycomb lattice than 2D square lattice. This is due to the fact that the number of NNN sites is equal to six, which is the double of NN sites in the 2D honeycomb lattice. Meanwhile, the number of NNN sites is equal to four which is equal to NN sites in 2D square lattice. We therefore conclude that by changing the ratio between NNN and NN sites in the 2D lattice one can tune the sensitivity for NNN hopping effects.
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