Strongly correlated electron system in the magnetic field

TL;DR

This paper investigates the energy spectrum of the 2D t-J model under a magnetic field, revealing oscillations in the density of states linked to van Hove singularities and strong electron correlations, with implications for cuprate superconductors.

Contribution

It demonstrates how strong correlations modify Landau subbands and cause modulation of quantum oscillations, providing insights into the electronic structure of correlated materials.

Findings

Oscillations in the density of states at the Fermi level as a function of 1/B.

Modulation of oscillation amplitude related to van Hove singularities.

Oscillation frequency comparable to that observed in underdoped cuprates.

Abstract

The energy spectrum of the two-dimensional t-J model in a perpendicular magnetic field is investigated. The density of states at the Fermi level as a function of the inverse magnetic field $\frac{1}{B}$ reveals oscillations in the range of hole concentrations $0.08<x<0.18$. In the used approximation zero-field Fermi surfaces are large for these $x$, and oscillation frequencies conform with such Fermi surfaces. However, the amplitude of these oscillations is modulated with a frequency which is smaller by an order of magnitude. The appearance of this modulation is related to van Hove singularities in the Landau subbands, which traverse the Fermi level with changing $B$. The singularities are connected with bending the Landau subbands due to strong electron correlations. The frequency of the modulation is of the same order of magnitude as the quantum oscillation frequency observed in underdoped cuprates.