Talk given by

Dr. Angelika Knothe

National Graphene Institute

University of Manchester

UK

Abstract:

We theoretically investigate the properties electrostatically confined nanostructures in 
gapped bilayer graphene (BLG). We show how the spectrum of subbands in a quantum 
wire in gapped BLG, and the energy levels in a quantum dot, manifest the minivalley 
structure and Berry curvature via the associated magnetic moment of the states in the 
low-energy bands. These features determine the degeneracies of the low-energy 
minibands / -levels and their valley splitting, which develops linearly in a weak magnetic 
field. In a quantum point contact, magneto-conductance reflects such degeneracies in 
the heights of the first conductance steps which develop upon the increase of the channel 
doping: 8e^2 /h steps in a wide channel in BLG with a large gap, 4e^2 /h steps in narrow 
channels, all splitting into a staircase of 2e^2 /h steps upon lifting valley degeneracy by a 
magnetic field B. For quantum dots, we investigate how optical selection rules are 
influenced by the minivalleys and the orbital magnetic moment, as well as by shapes of the 
confinement.

References:

A. Knothe and V. Fal’ko, Phys. Rev. B 98, 155435 (2018)
H. Overweg, A. Knothe, V. I. Fal’ko, K. Ensslin, T. Ihn, et al., arXiv:1809.01920
R. Kraft, I.V. Krainov, V. Gall, A.P. Dmitriev, R. Krupke, I.V. Gornyi, R. 
Danneau, arXiv:1809.02458