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

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 a 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 YBa2Cu3O6+delta