Fermi Surface Reconstruction and Quantum Oscillations in Underdoped YBa$_2$Cu$_3$O$_{7-x}$ Modeled in a Single Bilayer with Mirror Symmetry Broken by Charge Density Waves

TL;DR

This paper models the Fermi surface reconstruction in underdoped YBa2Cu3O7-x using a bilayer approach with charge density waves, explaining quantum oscillation data and the effects of spin-orbit interactions and pseudogap.

Contribution

It introduces a minimal bilayer model incorporating CDW, spin-orbit effects, and pseudogap to explain quantum oscillation phenomena in cuprate superconductors.

Findings

Qualitative agreement with observed quantum oscillation frequencies.

Explanation of fourfold symmetry in tilted magnetic fields.

Prediction of magnetic breakdown effects on QO spectrum.

Abstract

Hole-doped high-temperature cuprate superconductors below optimum doping have small electron-like Fermi surfaces occupying a small fraction of the Brillouin zone. There is strong evidence that this is linked to charge density wave (CDW) order, which reconstructs the large hole-like Fermi surfaces predicted by band structure calculations . Recent experiments have revealed the structure of the two CDW components in the benchmark bilayer material YBa$_2$Cu$_3$O$_{7-x}$ in high field where quantum oscillation (QO) measurements are performed. We have combined these results with a tight-binding description of the bands in an isolated bilayer to give a minimal model revealing the essential physics of the situation. Here we show that this approach, combined with the effects of spin-orbit interactions and the pseudogap, gives a good qualitative description of the multiple frequencies seen in the QO observations in this material. Magnetic breakdown through weak CDW splitting of the bands will lead to a field-dependence of the QO spectrum and to the observed fourfold symmetry of the results in tilted fields.