Landau quantization near generalized Van Hove singularities
Magnetic breakdown and orbit networks
V. A. Zakharov (Universiteit Leiden)
A. Mert Bozkurt (TU Delft - QuTech Advanced Research Centre, TU Delft - QRD/Wimmer Group, Kavli institute of nanoscience Delft)
AR Akhmerov (Kavli institute of nanoscience Delft, TU Delft - QN/Akhmerov Group)
D. Oriekhov (Universiteit Leiden)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
We develop a theory of magnetic breakdown (MB) near high-order saddle points in the dispersions of two-dimensional materials, where two or more semiclassical cyclotron orbits approach each other. MB occurs due to quantum tunneling between several trajectories, which leads to nontrivial scattering amplitudes and phases. We show that for any saddle point this problem can be solved by mapping it to a scattering problem in a 1D tight-binding chain. Moreover, the occurrence of magnetic breakdown on the edges of the Brillouin zone facilitates the delocalization of the bulk Landau level states and the formation of 2D orbit networks. These extended network states compose dispersive mini bands with finite energy broadening. This effect can be observed in transport experiments as a strong enhancement of the longitudinal bulk conductance in a quantum Hall bar. In addition, it may be probed in STM experiments by visualizing bulk current patterns.