Spectrum Collapse of Disordered Dirac Landau Levels as Topological Non-Hermitian Physics
Abstract
We investigate disorder effects on Landau levels in Dirac electron systems with the use of a non-Hermitian quasiparticle Hamiltonian formalism. This formalism reveals that spin-dependent scattering rates induce the spectrum collapse of Landau levels, i.e., the disappearance of the energy gaps between n- and −n-th levels under a finite external magnetic field. The spectrum collapse occurs in both weak and strong magnetic field regimes, thus showing a reentrant behavior. Particularly, in the strong magnetic field regime, in contrast to naive expectation, the increase of a magnetic field stabilizes the spectrum collapse of Dirac Landau levels. Furthermore, it is revealed that the spectrum collapse is associated with the emergence of a vortex texture with a topological winding number of a complex energy spectrum of the non-Hermitian system.
- Publication:
-
Journal of the Physical Society of Japan
- Pub Date:
- July 2021
- DOI:
- 10.7566/JPSJ.90.074703
- arXiv:
- arXiv:2004.11014
- Bibcode:
- 2021JPSJ...90g4703M
- Keywords:
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- Condensed Matter - Mesoscale and Nanoscale Physics;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- 8 pages,4 figures