Fermi pockets and quantum oscillations in specific heat of YBCO in the presence of disorder

TL;DR

This paper models the Fermi surface topology and quantum oscillations in the specific heat of YBCO in the pseudogap phase, highlighting the effects of disorder and magnetic field on Fermi pockets and oscillation phenomena.

Contribution

It introduces a chiral d-density wave model to analyze Fermi surface distortions and quantum oscillations in YBCO, incorporating disorder and anisotropy effects.

Findings

Fermi pockets around anti-nodal regions are identified at zero magnetic field.

Quantum oscillations in specific heat occur between 17 T and 53 T in weak disorder.

Pomeranchuk distortion affects Fermi surface topology when anisotropy is non-zero.

Abstract

We investigate a chiral d-density wave (CDDW) mean field model Hamiltonian in the momentum space suitable for the hole-doped cuprates, such as YBCO, in the pseudo-gap phase to obtain the Fermi surface(FS)topologies, including the anisotropy parameter(\'Epsilon) and the elastic scattering by disorder potential (|v0|). For \'Epsilon = 0, the chemical potential {\mu} = - 0.27 eV for 10% doping level, and |v0| \geq |t| (where |t| = 0.25 eV is the first neighbor hopping), at zero/non-zero magnetic field (B), the FS on the first Brillouin zone are found to correspond to Fermi pockets around anti-nodal regions and barely visible patches around nodal regions. For \'Epsilon \neq 0, we find Pomeranchuk distortion of FS. We next relate our findings regarding FS to the magneto-quantum oscillations in the electronic specific heat. Since the nodal quasi-particle energy values for B = 0 are found to be greater than {\mu} for |v0| \geq |t|, the origin of the oscillations for non-zero B corresponds to the Fermi pockets around anti-nodal regions. The oscillations are shown to take place for 17 T \leq B \leq 53 T and beyond in the weak disorder regime (|v0|=0.25eV) only.