PhD Mid-term Seminar Series: Ferroelectric hysteresis in single layer Graphene/hBN moiré superlattice

Ferroelectric materials have the unique ability to maintain and reverse electric polarization with an external applied electric field, making them valuable for applications such as non-volatile random-access memory, transducers, actuators and electro-optic modulators.[1] Traditionally, this property was thought to be exclusive to insulating materials, as insulators are crucial for sustaining polarization and enabling field-induced switching. However, recent research on two-dimensional (2D) material has shown that ferroelectric properties can also exist in semiconductors and metals.[2] Recently, emergent unconventional ferroelectricity has been demonstrated in the moiré superlattices of bilayer graphene and hexagonal boron nitride (hBN), hosting non-centrosymmetric stacking order [3,4]. Whether such phenomenon can persist in non-centrosymmetric single layer graphene (SLG)-hBN moiré superlattices has still remained elusive. In this talk, we demonstrate a ferroelectric response in SLG-hBN moiré superlattice. This hysteretic behavior persists from 2K to room temperature, offering further opportunities for high-mobility, ultrathin non-volatile devices. 

References: 

C. Wang et al., Nat. Mater. 22, 542 (2023). 

S. Bhowal and N. A. Spaldin, Annu. Rev. Mater. Res. 53, 53 (2023). 

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