posted on 2022-09-16, 20:43authored byFabian
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 disorderspatial variations in the interlayer
potential differenceas 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.