探测以Ca $_2$ N为载体的石墨烯的发散van Hove奇异性：作为固态掺杂剂的层状掺杂剂
Probing a divergent van Hove singularity of graphene with a Ca$_2$N support: a layered electride as a solid-state dopant
摘要：
以Ca $_2$ N为代表的层状晶体是一类新型的准二维低功函数材料。使用第一性原理计算，我们已经表明，沉积在Ca $_2$ N上的石墨烯层被掺杂到$n=5\times 10^{14}$ cm $^{-2}$，其费米能级与石墨烯$π^*$带中的色散范霍夫奇点对准。对于在Ca $_2$ N上的双层石墨烯，内部石墨烯层被掺杂到相同的水平，而外部石墨烯层的掺杂要适度得多。这一发现开启了一个有趣的可能性，使用分层的晶体来探索范霍夫物理学。的功函数的变化与石墨烯层的数量，我们解释的组成材料和它们的键合的奇特的电子结构。
英文摘要：
Layered electrides, as typified by Ca$_2$N, are a new class of quasi-two-dimensional materials with low work functions. Using first-principles calculations, we have shown that a graphene layer deposited on Ca$_2$N is doped to $n=5\times 10^{14}$ cm$^{-2}$ with its Fermi level aligned with the logarithmically divergent van Hove singularity in the graphene $π^*$ band. For bilayer graphene on Ca$_2$N, the inner graphene layer is doped to the same level, while the doping of the outer graphene layer is much more modest. This finding opens an interesting possibility of using layered electrides for the exploration of van Hove physics. The work function changes nonmonotonically with the number of graphene layers, which we explain in terms of the peculiar electronic structures of the constituent materials and their bonding.
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