Central peak in the pseudogap of high T_c superconductors

TL;DR

This paper investigates the pseudogap phenomenon in high T_c superconductors, revealing a central peak caused by antiferromagnetic correlations and zero-point magnon motion, aligning well with experimental observations.

Contribution

It introduces a quantum low-temperature regime where the pseudogap arises from magnon zero-point motion, providing a new perspective on the pseudogap's origin in high T_c superconductors.

Findings

Identification of a central peak in the pseudogap near the vH singularity.

Quantitative agreement of spectral functions with experimental data.

Reproduction of the peak behavior relative to the Fermi energy.

Abstract

We study the effect of antiferromagnetic (AF) correlations in the three-band Emery model, with respect to the experimental situation in weakly underdoped and optimally doped BSCCO. In the vicinity of the vH singularity of the conduction band there appears a central peak in the middle of a pseudogap, which is in an antiadiabatic regime, insensitive to the time scale of the mechanism responsible for the pseudogap. We find a quantum low-temperature regime corresponding to experiment, in which the pseudogap is created by zero-point motion of the magnons, as opposed to the usual semiclassical derivation, where it is due to a divergence of the magnon occupation number. Detailed analysis of the spectral functions along the (pi,0)-(pi,pi) line show significant agreement with experiment, both qualitative and, in the principal scales, quantitative. The observed slight approaching-then-receding of both the wide and narrow peaks with respect to the Fermi energy is also reproduced. We conclude that optimally doped BSCCO has a well-developed pseudogap of the order of 1000 K. This is only masked by the narrow antiadiabatic peak, which provides a small energy scale, unrelated to the AF scale, and primarily controlled by the position of the chemical potential.