Density Wave States in the Presence of an External Magnetic Field

Abstract

We investigate the effect that density-wave states have on the Hofstadter Butterfly. We first review the problem of the $d$-density wave on a square lattice and then numerically solve the $d$-density wave problem when an external magnetic field is introduced. As the $d$-density wave condensation strength is tuned the spectrum evolves through three topologically distinct butterflies, and an unusual quantum Hall effect is observed. The chiral $p+ip$-density wave state demonstrates drastically different Hofstadter physics--inducing a destruction of the gaps in the butterfly which causes electrons' cyclotron orbits to not obey any type of Landau quantization, and the creation of a large gap in the spectrum with Hall conductance ${\sigma }_{xy}$=0. To investigate the quantum phases in the system we perform a multifractal analysis of the single particle wavefunctions. We find that tuning the $d$-density wave strength at a generic value of magnetic flux controls a metal-metal transition at charge neutrality where the wavefunction multifractality occurs near band touching events. In the $p+ip$ case we observe another metal-metal transition near a band touching event which is seperated by a quasi-insulating island state occuring at charge neutrality near strip dimerization of the lattice.

arXiv comment10 pages, 19 figures

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Cited by in corpus (3)

• Unusual magnetotransport in twisted bilayer graphene
• A higher-dimensional quasicrystalline approach to the Hofstadter and Fibonacci butterflies topological phase diagram and band conductance: symbolic sequences, Sturmian coding and self-similar rules at all magnetic fluxes
• Geometry, Number Theory and the Butterfly Spectrum of Two-Dimensional Bloch Electrons