Cantor spectra of magnetic chain graphs

Abstract

We demonstrate a one-dimensional magnetic system can exhibit a Cantor-type spectrum using an example of a chain graph with $\delta$ coupling at the vertices exposed to a magnetic field perpendicular to the graph plane and varying along the chain. If the field grows linearly with an irrational slope, measured in terms of the flux through the loops of the chain, we demonstrate the character of the spectrum relating it to the almost Mathieu operator.

15 pages, 2 figures; Section 3 argument revised, three references added

References in corpus (7)

• Hofstadter's butterfly in moire superlattices: A fractal quantum Hall effect
• Cloning of Dirac fermions in graphene superlattices
• Spectra of self-adjoint extensions and applications to solvable Schroedinger operators
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Cited by in corpus (2)

• Cantor spectrum of graphene in magnetic fields
• A family of quantum graph vertex couplings interpolating between different symmetries