Emergent Dirac Gullies and Gully-Symmetry-Breaking Quantum Hall States in ABA Trilayer Graphene
Emergent Dirac Gullies and Gully-Symmetry-Breaking Quantum Hall States in ABA Trilayer Graphene
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ABA 三层石墨烯中涌现的狄拉克沟壑和沟壑对称破缺量子霍尔态
DOI：
10.1103/physrevlett.121.167601
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发表时间：
2018
影响因子：
8.6
通讯作者：
Young, A. F.
中科院分区：
文献类型：
--
作者：
Zibrov, A. A.;Rao, P.;Kometter, C.;Spanton, E. M.;Li, J. I. A.;Dean, Cory R.;Taniguchi, T.;Watanabe, K.;Serbyn, M.;Young, A. F.
我们报告高品质的量子电容测量，石墨和六方氮化硼封装的Bernal堆叠三层石墨烯器件。在零外加磁场下，我们观察到一些电子密度和电位移调谐功能的费米表面拓扑结构的变化相关的电子压缩性。在高位移场和低密度下，强烈的三角弯曲在每个山谷中产生三个新的狄拉克锥，我们称之为“沟”。这些沟壑以六边形布里渊区的拐角为中心，并通过三重旋转对称性相关联。在低磁场下，沟道表现为朗道能级简并度从2变为3。在这些三重态朗道能级内的整数填充处也观察到弱不可压缩态，Hartree-Fock分析表明，这与库仑驱动的自发破坏旋转对称性的非线性相位有关。
We report on quantum capacitance measurements of high quality, graphite and hexagonal boron nitride encapsulated Bernal stacked trilayer graphene devices. At zero applied magnetic field, we observe a number of electron density- and electrical displacement-tuned features in the electronic compressibility associated with changes in Fermi surface topology. At a high displacement field and low density, strong trigonal warping gives rise to three new emergent Dirac cones in each valley, which we term “gullies.” The gullies are centered around the corners of a hexagonal Brillouin zone and related by threefold rotation symmetry. At low magnetic fields of, the gullies manifest as a change in the degeneracy of the Landau levels from two to three. Weak incompressible states are also observed at integer filling within these triplet Landau levels, which a Hartree-Fock analysis indicates are associated with Coulomb-driven nematic phases that spontaneously break rotation symmetry.