Fig. 2: BLG domain size and stacking order control*
[Reprinted by permission from Macmillan Publishers Ltd: Nature Nanotechnology ©2016]
Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical and requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability.
Fig. 1b: Wilson lines and effectively degenerate Bloch bands.* [Reprinted with permission from AAAS ©2016.]
Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high-energy theories, quantum information, and condensed-matter physics. In condensed-matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multiband systems.
Physics Concentrators: Tara Aida, Mark Arildsen, Steven Barroqueiro, Roman Berens, Amir Bitran, Jimmy Castano, Nicky Charles, Aftab Chitalwala, Alex Coeytaux, Keno Fischer, Tudor Giurgica-Tiron, Connor Harris, Achim Harzheim, Roger Huang, Grace Huckins, Natalie Janzow, Patrick Komiske, Michael Landry, Dennis Lee, Peter Lu, Aaron Markowitz, Kyle Matsuda, Nat Mayer, Eric Metodiev, Whitney Nimitpattana, Matt Pasquini, Ray Qian, David Roberts, Ellen Robo, Sadik Shahidain, Austin Shin, Olivier Simon, Zack Soule, Erik Tamre, Will Tobias, Joy Wang, Lucian Wang, Annie Wei, Daniel Windham, Cyndia Yu, Daniel Yue, Alan Zhou, Ting Zhou
(a) Schematic of the measurement apparatus used in the present work. The initial state can be populated using either (b) an optical pumping scheme similar to that used in ACME I, or (c) a STIRAP scheme.* [Reprinted with permission from APS]