Theory of non-Fermi liquid and pairing in electron-doped cuprates

TL;DR

This paper uses the spin-fermion model to analyze the normal state and pairing mechanisms in electron-doped cuprates, revealing lower critical temperatures and non-monotonic d-wave gaps influenced by Fermi surface curvature.

Contribution

It provides a theoretical framework explaining the reduced T_c and non-monotonic gap structure in electron-doped cuprates, extending understanding from hole-doped counterparts.

Findings

Normal state properties match experimental observations.

T_c in electron-doped cuprates is around 10K, lower than hole-doped.

Non-monotonic d_{x^{2}-y^{2}} gap persists even when hot spots merge.

Abstract

We apply the spin-fermion model to study the normal state and pairing instability in electron-doped cuprates near the antiferromagnetic QCP. Peculiar frequency dependencies of the normal state properties are shown to emerge from the self-consistent equations on the fermionic and bosonic self-energies, and are in agreement with experimentally observed ones. We argue that the pairing instability is in the $d_{x^{2}-y^{2}}$ channel, as in hole-doped cuprates, but theoretical $T_{c}$ is much lower than in the hole-doped case. For the same hopping integrals and the interaction strength as in hole-doped materials, we obtain $T_{c}\sim10$K at the end point of the antiferromagnetic phase. We argue that a strong reduction of $T_{c}$ in electron-doped cuprates compared to hole-doped ones is due to critical role of the Fermi surface curvature for electron-doped materials. The $d_{x^{2}-y^{2}}$-pairing gap $\Delta(\mathbf{k},\omega)$ is strongly non-monotonic along the Fermi surface. The position of the gap maxima, however, does not coincide with the hot spots, as the non-monotonic $d_{x^{2}-y^{2}}$ gap persists even at doping when the hot spots merge on the Brillouin zone diagonals.