American Chemical Society
nl2c02119_si_001.pdf (1.86 MB)

Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene

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journal contribution
posted on 2022-09-16, 20:43 authored by Fabian R. Geisenhof, Felix Winterer, Anna M. Seiler, Jakob Lenz, Fan Zhang, R. Thomas Weitz
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.