arXiv subjects

M. -H. Liu

Publications and source records attributed to M. -H. Liu.

2 recordsLinked to original sources

arXiv2020

Anomalous Cyclotron Motion in Graphene Superlattice Cavities

We consider graphene superlattice miniband fermions probed by electronic interferometry in magneto-transport experiments. By decoding the observed Fabry-Pérot interference patterns together with our corresponding quantum transport simulations, we find that the Dirac quasiparticles originating from the superlattice minibands do not undergo conventional cyclotron motion but follow more subtle trajectories. In particular, dynamics at low magnetic fields is characterized by peculiar, straight trajectory segments. Our results provide new insights into superlattice miniband fermions and open up novel possibilities to use periodic potentials in electron optics experiments.

cond-mat.mes-hall↗

arXiv2009

Quantum interference in macroscopic crystals of non-metallic Bi$_2$Se$_3$

Photoemission experiments have shown that Bi$_2$Se$_3$ is a topological insulator. By controlled doping, we have obtained crystals of Bi$_2$Se$_3$ with non-metallic conduction. At low temperatures, we uncover a novel type of magnetofingerprint signal which involves the spin degrees of freedom. Given the mm-sized crystals, the observed amplitude is 200-500$\times$ larger than expected from universal conductance fluctuations. The results point to very long phase breaking lengths in an unusual conductance channel in these non-metallic samples. We discuss the nature of the in-gap conducting states and their relation to the topological surface states.

cond-mat.mes-hall↗