Theoretical investigation of a CDDW Hamiltonian for YBCO to explore the possibility of quantum oscillations in specific heat

TL;DR

This paper provides a theoretical analysis of a chiral d-density wave Hamiltonian in YBCO, revealing entropy discontinuities, origins of anomalous Nernst signals, and the potential for quantum oscillations in specific heat.

Contribution

It introduces a detailed theoretical model of CDDW in YBCO, highlighting entropy behavior, Nernst effect origins, and quantum oscillation possibilities not previously explored.

Findings

Entropy discontinuities at hot spots on the Brillouin zone boundary.

Chirality-induced anomalous Nernst signal near hot spots.

Potential quantum oscillations in specific heat under magnetic field.

Abstract

We investigate a chiral d-density wave (CDDW) mean field Hamiltonian in momentum space for the under-doped YBCO. We consider the commensurate density wave order which doubles the unit cell of the real space lattice and derive an expression for entropy in the CDDW state in the absence of magnetic field. We show that the transition to CDDW state gives rise to the occurrence of discontinuities in the entropy density difference between the CDDW state and the normal state at eight points(Hot spots) on the boundary of the reduced Brillouin zone. The chirality induced anomalous Nernst signal is shown to arise mainly from the points close to these Hot spots and not from the hole pockets as reported by the previous authors. We also show the possibility of quantum oscillations in the specific heat for the system under consideration in the presence of a changing magnetic field.