An Atomistic Insight into Moire Reconstruction in Twisted Bilayer Graphene beyond the Magic Angle

Twisted bilayer graphene exhibits electronic properties strongly correlated with the size and arrangement of moir & eacute; patterns. While rigid rotation of the two graphene layers results in a moir & eacute; interference pattern, local rearrangements of atoms due to interlayer van der Waals interactions result in atomic reconstruction within the moir & eacute; cells. Manipulating these patterns by controlling the twist angle and externally applied strain provides a promising route to tuning their properties. Atomic reconstruction has been extensively studied for angles close to or smaller than the magic angle (theta(m) = 1.1 degrees). However, this effect has not been explored for applied strain and is believed to be negligible for high twist angles. Using interpretive and fundamental physical measurements, we use theoretical and numerical analyses to resolve atomic reconstruction in angles above theta(m). In addition, we propose a method to identify local regions within moir & eacute; cells and track their evolution with strain for a range of representative high twist angles. Our results show that atomic reconstruction is actively present beyond the magic angle, and its contribution to the moir & eacute; cell evolution is significant. Our theoretical method to correlate local and global phonon behavior further validates the role of reconstruction at higher angles. Our findings provide a better understanding of moir & eacute; reconstruction in large twist angles and the evolution of moir & eacute; cells under the application of strain, which might be potentially crucial for twistronics-based applications.