Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Topology: Quantum Hall Systems
TT 11.2: Vortrag
Dienstag, 6. September 2022, 09:45–10:00, H10
Quantum Hall critical phase at topological insulator surfaces — •Johannes Dieplinger1, Mateo Moreno-Gonzalez2, Soumya Bera3, Martin Puschmann1, Matthew Foster4, Ferdinand Evers1, and Alexander Altland2 — 1University of Regensburg, Regensburg, Germany — 2Universiy of Cologne, Cologne, Germany — 3IIT Bombay, Mumbai, India — 4Rice University, Houston, Texas, USA
We show that an AIII three-dimensional topological insulator, when tuned away from the critical point at zero energy, realizes a finite class A critical phase on its surface, i.e. a continuum of quantum Hall critical states, instead of an naively expected quantum Hall insulator. Criticality is characterized numerically via an analysis of the multifractal exponents of the wave functions at the surface of the three dimensional bulk.
This numerical work supports a recently proposed first principle theory explaining the existence of the quantum Hall critical phase. Open questions remain concerning the nature of disordered surface states with higher topological index.