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

Geisenhof, Fabian R.; Winterer, Felix; Seiler, Anna M.; Lenz, Jakob; Zhang, Fan und Weitz, R. Thomas (2022): Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene. In: Nano Letters, Bd. 22, Nr. 18: S. 7378-7385

Abstract

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.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 1530-6984
• Sprache: Englisch