Valleytronics

In many 2D materials, band edges are found at two corners of the first Brillouin zone called K and K′ valleys. The valley degree of freedom can be electrostatically manipulated to allow dissipationless information transfer and novel valleytronics device functionality, similar to spintronics. In our lab, we recently demonstrated two different device platforms capable of generating and manipulating valley-polarized current. The first one is utilizing nano-gating to configure a zero-dimensional PN junction hosting valley-chiral states. The second approach is engineering twisted multilayer devices with atomically-enhanced moiré Berry curvature hot spots, with valley currents that can be manipulated by tuning the inter-moiré reconstruction.

Tunable Atomically Enhanced Moiré Berry Curvatures in Twisted Triple Bilayer Graphene

Valley currents at moiré Berry curvature hot spot can be tuned with inter-moiré atomic reconstruction.

Konstantin Davydov, Ziyan Zhu, Noah Friedman, Ethan Gramowski, Yaotian Li, Jack Tavakley, Kenji Watanabe, Takashi Taniguchi, Mitchell Luskin, Efthimios Kaxiras, Ke Wang, Physical Review B 111, L161120 (2025) (Letter & Editors' Suggestion)

Easy-to-Configure Zero-Dimensional Valley-Chiral Modes in a Graphene Point Junction

In a graphene point junction, switchable valley current with high valley polarization can be easily configured.

Konstantin Davydov, Xi Zhang, Wei Ren, Matthew Coles, Logan Kline, Bryan Zucker, Kenji Watanabe, Takashi Taniguchi, Ke Wang, Science Advances, eadp6296 (2024)