Hysteresis and anomalous gate screening in aligned graphene/BN systems

Moiré potentials in few-layer graphene aligned to boron nitride (BN) can generate a variety of emergent physical phenomena. As a prominent recent example, anomalous gate screening and hysteresis of the electrical resistance have been observed in bilayer graphene aligned to BN [1]. However, the mechanism underlying this effect and the precise role of the moiré potential remain unclear. In this work, we perform a systematic study of few-layer graphene devices in which we control the alignment of both the top and bottom BN with the graphene. We probe the role of the moiré potential by surveying all possible BN/graphene/BN alignment configurations, distinguishing between and alignment using Raman spectroscopy and second harmonic generation. We find that the hysteresis persists above room temperature, calling into question the role of correlations in establishing this effect. Our work is a significant step towards both understanding the nature of this phenomenon and implementing these devices for useful electronics applications.



1) Z. Zheng, et al., Nature, 588, 71–76 (2020)