Cuprate Superconductors in the Vicinity of a Pomeranchuk Instability

TL;DR

This paper suggests that cuprate superconductors are near a d-wave Pomeranchuk instability, explaining anisotropic magnetic excitations and structural transition effects through a comprehensive theoretical study.

Contribution

It introduces a theoretical framework linking cuprate superconductors to a d-wave Pomeranchuk instability, explaining magnetic excitation behaviors.

Findings

Explains xy anisotropy of magnetic excitations in YBa2Cu3O_y.

Accounts for changes in magnetic incommensurability at structural transitions.

Provides understanding of magnetic excitation differences in Y-based and La-based cuprates.

Abstract

We propose that cuprate superconductors are in the vicinity of a spontaneous d-wave type Fermi surface symmetry breaking, often called a d-wave Pomeranchuk instability. This idea is explored by means of a comprehensive study of magnetic excitations within the slave-boson mean-field theory of the t-J model. We can naturally understand the pronounced xy anisotropy of magnetic excitations in untwinned YBa_{2}Cu_{3}O_{y} and the sizable change of incommensurability of magnetic excitations at the transition temperature to the low-temperature tetragonal lattice structure in La_{2-x}Ba_{x}CuO_{4}. In addition, the present theoretical framework allows the understanding of the similarities and differences of magnetic excitations in Y-based and La-based cuprates.