Hofstadter Butterfly and Broken-Symmetry Quantum Hall States in \alpha-Type Organic Dirac Fermion Systems
Abstract
The electronic state of \alpha-type organic Dirac fermion systems such as \alpha-(ET)_2I_3 or \alpha-(BETS)_2I_3 has been studied under magnetic fields using the four-band tight-binding model with Peierls phase factors. The validity of the Dirac fermion picture in these materials was confirmed by the generated Hofstadter butterfly and its Chern numbers. The four-component envelope function of the N = 0 Landau level with valley degeneracy was studied. It was found that the two degenerate valley states have different weights on A and A' molecules connected by inversion. This feature is also recognized for the N = 0 spin-split Landau levels under the Zeeman effect and the spin-orbit interaction. The spontaneous valley symmetry breaking in the N = 0 Landau levels due to the exchange interaction results in the \nu = 1 and -1 quantum Hall states accompanied by the spatial charge and spin modulations in a unit cell.
Keywords
Cite
@article{arxiv.2312.09413,
title = {Hofstadter Butterfly and Broken-Symmetry Quantum Hall States in \alpha-Type Organic Dirac Fermion Systems},
author = {Toshihito Osada},
journal= {arXiv preprint arXiv:2312.09413},
year = {2024}
}
Comments
16 pages, 4 figures