Quantum-critical pairing in electron-doped cuprates

TL;DR

This paper revisits spin-mediated superconducting pairing at an antiferromagnetic quantum-critical point in electron-doped cuprates, incorporating umklapp processes to accurately evaluate the normal state self-energy and critical temperature.

Contribution

It introduces the inclusion of umklapp processes into the analysis, leading to a more precise calculation of the critical temperature in electron-doped cuprates.

Findings

Self-energy exhibits Fermi-liquid behavior.

Calculated T_c  10 K, consistent with experiments.

Renormalized quasiparticle parameters near optimal doping.

Abstract

We revisit the problem of spin-mediated superconducting pairing at the antiferromagnetic quantum-critical point with the ordering momentum ({\pi},{\pi}) = 2k_F. The problem has been previously considered by one of the authors. However, it was later pointed out that that analysis neglected umklapp processes for the spin polarization operator. We incorporate umklapp terms and re-evaluate the normal state self-energy and the critical temperature of the pairing instability. We show that the self-energy has a Fermi-liquid form and obtain the renormalization of the quasiparticle residue Z, the Fermi velocity, and the curvature of the Fermi surface. We argue that the pairing is a BCS-type problem, but go one step beyond the BCS theory and calculate the critical temperature T_c with the prefactor. We apply the results to electron-doped cuprates near optimal doping and obtain T_c \geq 10 K, which matches the experimental results quite well.