In-situ stress-induced modulation of Moiré pattern configuration and electromechanical response in twisted 2D heterostructure

Moiré patterns, with the unique stacking configurations and complex electromechanical coupling behaviors, have emerged as a promising platform for exploring novel physical phenomena. However, research on polarization in Moiré patterns remains in its early stages, and the origin and distribution of spontaneous polarization remain unknown. In this work, the out-of-plane polarization distribution of Moiré superlattices in twisted h-BN (t-BN) with a small twist angle is meticulously delineated using piezoelectric force microscopy (PFM) with quadrature phase differential interferometry (QPDI) analyzer. The polarization of AB/BA stacking domains and saddle points regions has been detected, where opposite polarization regions exhibit a 180 degrees phase difference. The strain within the Moiré pattern significantly alters the polarization distribution at saddle points regions, leading to pronounced differences in the electromechanical behaviors between the inner Moiré domain and domain wall regions. Moreover, in-situ stress can modify the saddle points regions, leading to an expansion of these regions and a larger electromechanical response with increasing stress. This work not only deepens the comprehension of the electromechanical performance of Moiré materials, but also lays a solid groundwork for the designing new ferroelectric materials and manipulating their electromechanical response.