Universal magnetic oscillations of DC conductivity in the incoherent regime of correlated systems

TL;DR

This paper reveals universal magnetic oscillations in DC conductivity of correlated systems, including unconventional high-frequency oscillations at high temperatures, supported by theoretical analysis and experimental agreement.

Contribution

It demonstrates the existence of additional magnetic oscillations beyond conventional quantum oscillations in incoherent regimes of correlated systems.

Findings

Identification of high-frequency oscillations at elevated temperatures.

Agreement with experimental observations in graphene superlattices.

Role of electronic incoherence and current vertex in oscillation behavior.

Abstract

Using the dynamical mean field theory we investigate the magnetic field dependence of DC conductivity in the Hubbard model on the square lattice, fully taking into account the orbital effects of the field introduced via the Peierls substitution. In addition to the conventional Shubnikov-de Haas quantum oscillations, associated with the coherent cyclotron motion of quasiparticles and the presence of a well-defined Fermi surface, we find an additional oscillatory component with a higher frequency that corresponds to the total area of the Brillouin zone. These paradigm-breaking oscillations appear at elevated temperature. This finding is in excellent qualitative agreement with the recent experiments on graphene superlattices. We elucidate the key roles of the off-diagonal elements of the current vertex and the incoherence of electronic states, and explain the trends with respect to temperature and doping.