Transport properties of the twisted bilayer graphene at different twist angles

22/01/2020 @ 11:00 AM – 12:00 PM Asia/Singapore Timezone
S16 Level 6 – Theory Common Conference Room

Speaker: Dr Alexey Berdyugin
Affiliation: University of Manchester
Host: Dr Ivan Verzhbitskiy (on behalf of Assoc Prof Eda Goki)
Location: Click HERE for directions

Abstract Details: In my talk, I will report our recent results on twisted bilayer graphene. First, I will focus on a regime when the twist angle is higher than the magic angle. The high quality of our samples allowed us to measure the transverse magnetic focusing effect and utilize it study the miniband structure of this metal. The interlayer displacement field enabled us to lift the minivalley degeneracy and observe a minivalley polarized magnetic focusing.

Next, I will cover the regime with the twist angle much smaller than the magic. At very small twist angles of ~0.1 degree twisted bilayer graphene exhibits strain-accompanied lattice reconstruction that results in submicron-size triangular domains with standard, Bernal stacking. If the interlayer bias is applied to open an energy gap inside the domain regions making them insulating, such marginally twisted bilayer graphene is expected to remain conductive due to a triangular network of chiral one-dimensional states hosted by domain boundaries. In our work, we study electron transport through this network and report giant Aharonov-Bohm oscillations which persist up to 100K. At low temperature, we observe narrow minibands formed by the network of one-dimensional states inside the gap.

About the Speaker: Alexey Berdyugin was born in 1993 in a small-town V-Pyshma (Russia) which locates on a border between Europe and Asia. He got his master’s degree at Moscow Institute of Physics and Technology during which he studied energy relaxation of electron system in graphene.

He joined the University of Manchester Condensed Matter Physics group in 2016. His current research interest stays within the transport properties of the novel van der Waals materials. First of all, he studies hydrodynamic current propagation regime in a presence of the magnetic field in graphene/hBN heterostructures and control over electron-electron interaction via proximity gating. Also, he is interested in several kinds of graphene superlattices such as twisted bilayer graphene and aligned graphene/hBN, where he studies the miniband structure of those materials, Hofstadter butterfly physics, and lattice reconstruction effects.