Regensburg 2022 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 23: Computational Materials Modelling: Magnetic & Electrical Properties

MM 23.9: Vortrag

Mittwoch, 7. September 2022, 18:00–18:15, H44

Supermetal-insulator transition in a non-Hermitian network model — •Hui Liu¹, Jhih-Shih You², Shinsei Ryu³, and Ion Cosma Fulga¹ — ¹IFW Dresden and Würzburg-Dresden Cluster of Excellence ct.qmat, Helmholtzstrasse 20, 01069 Dresden, Germany — ²Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan — ³Department of Physics, Princeton University, Princeton, New Jersey, 08540, USA

We study a non-Hermitian and non-unitary version of the two-dimensional Chalker-Coddington network model with balanced gain and loss. This model belongs to the class D^† with particle-hole symmetry† and hosts both the non-Hermitian skin effect as well as exceptional points. By calculating its two-terminal transmission, we find a novel contact effect induced by the skin effect, which results in a non-quantized transmission for chiral edge states. In addition, the model exhibits an insulator to "supermetal" transition, across which the transmission changes from exponentially decaying with system size to exponentially growing with system size. In the clean system, the critical point separating insulator from supermetal is characterized by a non-Hermitian Dirac point that produces a quantized critical transmission of 4, instead of the value of 1 expected in Hermitian systems. This change in critical transmission is a consequence of the balanced gain and loss. When adding disorder to the system, we find a critical exponent for the divergence of the localization length ν=1, which is the same as that characterizing the universality class of two-dimensional Hermitian systems in class D.