Lattice theory of pseudospin ferromagnetism in bilayer graphene: Competing interaction-induced quantum Hall states
Lattice theory of pseudospin ferromagnetism in bilayer graphene: Competing interaction-induced quantum Hall states
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DOI：
10.1103/physrevb.83.115408
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发表时间：
2011-03-07
影响因子：
3.7
通讯作者：
MacDonald, Allan H.
中科院分区：
文献类型：
--
作者：
Jung, Jeil;Zhang, Fan;MacDonald, Allan H.
在平均场理论中，双层石墨烯的大质量狄拉克费米子模型具有一个具有电荷间隙和味道依赖的自发层间电荷转移的破反对称基态家族。我们使用晶格Hartree-Fock模型来探索石墨烯双层的晶格尺度物理，这对有序能量尺度和不同有序态之间的竞争有很大的影响。我们发现在晶格模型中反转对称性仍然是破缺的，并估计转移的面密度近似为每个碳原子10（-5）个电子，相关的能隙近似为10（-2）eV，有序凝聚能近似为每个碳原子10（-7）eV，并且竞争有序态之间的能量差类似于每个碳原子10（-9）eV。我们发现，与量子化谷霍尔效应的状态是最低的能量，但外部磁场的耦合到自发轨道的时刻有利于打破时间逆对称态，量子化的异常霍尔效应。我们的理论预测的非单调行为的带隙在中性层之间的电位差，在定性与最近的实验。
In mean-field theory, bilayer graphene's massive Dirac fermion model has a family of broken-inversion-symmetry ground states with charge gaps and flavor-dependent spontaneous interlayer charge transfers. We use a lattice Hartree-Fock model to explore the lattice scale physics of graphene bilayers, which has a strong influence on ordering energy scales and on the competition between distinct ordered states. We find that inversion symmetry is still broken in the lattice model and estimate that the transferred areal densities are similar to 10(-5) electrons per carbon atom, that the associated energy gaps are similar to 10(-2) eV, that the ordering condensation energies are similar to 10(-7) eV per carbon atom, and that the differences in energy between competing ordered states is similar to 10(-9) eV per carbon atom. We find that states with a quantized valley Hall effect are lowest in energy, but that the coupling of an external magnetic field to spontaneous orbital moments favors the broken-time-reversal-symmetry states that have quantized anomalous Hall effects. Our theory predicts nonmonotonic behavior of the band gap at neutrality on the potential difference between layers, in qualitative agreement with recent experiments.