Singlet versus triplet particle-hole condensates in quantum oscillations in cuprates

TL;DR

This paper compares singlet and triplet particle-hole condensates in cuprates using quantum oscillation measurements to distinguish their order parameters, providing theoretical insights relevant to recent experimental findings.

Contribution

The study offers a theoretical comparison of spin density wave, singlet d-density wave, and triplet d-density wave in the context of quantum oscillations in cuprates.

Findings

Spin zero in oscillation amplitude indicates a singlet order parameter.

Triplet order parameters may or may not show a spin zero depending on Fermi surface orbits.

Analysis helps interpret recent experimental results in YBa2Cu3O6+δ.

Abstract

Quantum oscillations in a tilted magnetic field offer the possibility of distinguishing singlet versus triplet order parameters in the particle hole channel provided the measurements reflect a putative ``normal'' state of a density wave obtained by applying by high magnetic field at low temperatures. A theoretical analysis is given that compares spin density wave, a singlet $d$-density wave, and a triplet $d$-density wave. While the existence of a spin zero in the oscillation amplitude is a necessary consequence of a singlet order parameter, a triplet order parameter may or may not exhibit a spin zero, making it a quantitative issue that depends on the actual extremal orbits on the Fermi surface. Nonetheless, a theoretical analysis can shed light on the striking recent measurements in $\mathrm{YBa_{2}Cu_{3}O_{6+\delta}}$.