Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene
Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene
复制标题
电场无序对超净双层石墨烯破缺对称态的影响
DOI：
10.1021/acs.nanolett.2c02119
复制
发表时间：
2022
期刊：
影响因子：
10.8
通讯作者：
Weitz, R. Thomas
中科院分区：
文献类型：
--
作者：
Geisenhof, Fabian R.;Winterer, Felix;Seiler, Anna M.;Lenz, Jakob;Zhang, Fan;Weitz, R. Thomas
当忽略三角翘曲时，双层石墨烯（BLG）具有多个内部自由度和低至电荷中性点的恒定状态密度。因此，它容易受到各种竞争基态的影响。然而，由于相互作用与无序的相互作用，对基态的相干实验测定一直具有挑战性。在这里，我们对一系列双门控独立式 BLG 器件进行了广泛的输运研究，并将层反铁磁体确定为基态，在所有器件上具有连续强度。该强度与电场中状态的宽度相关。我们系统地确定了电场无序（层间电位差的空间变化）是造成观测的主要来源。我们的研究结果首次指出了电场无序对 BLG 自发对称性破缺的重要性，并解决了关于其基态的长期争论。电场紊乱对于所有二维材料应该是普遍存在的。
Bilayer graphene (BLG) has multiple internal degrees of freedom and a constant density of states down to the charge neutrality point when trigonal warping is ignored. Consequently, it is susceptible to various competing ground states. However, a coherent experimental determination of the ground state has been challenging due to the interaction–disorder interplay. Here we present an extensive transport study in a series of dually gated freestanding BLG devices and identify the layer-antiferromagnet as the ground state with a continuous strength across all devices. This strength correlates with the width of the state in the electric field. We systematically identify electric-field disorder─spatial variations in the interlayer potential difference─as the main source responsible for the observations. Our results pinpoint for the first time the importance of electric-field disorder on spontaneous symmetry breaking in BLG and solve a long-standing debate on its ground state. The electric-field disorder should be universal to all 2D materials.