Tc is insensitive to magnetic interactions in high-Tc superconductors

TL;DR

This study investigates the relationship between magnetic interactions and superconducting transition temperature in cuprate high-Tc superconductors, revealing that the maximum Tc does not correlate with the magnetic exchange interaction J as previously thought.

Contribution

It demonstrates that variations in magnetic exchange interaction J do not directly influence the maximum Tc, challenging the magnetic pairing hypothesis in high-Tc superconductors.

Findings

Tcmax anticorrelates with J under internal pressure.

External pressure effects differ from internal pressure effects.

J is not the dominant energy scale for Tcmax.

Abstract

A quarter of a century after their discovery the mechanism that pairs carriers in the cuprate high-Tc superconductors (HTS) still remains uncertain. Despite this the general consensus is that it is probably magnetic in origin [1] so that the energy scale for the pairing boson is governed by J, the antiferromagnetic exchange interaction. Recent studies using resonant inelastic X-ray scattering strongly support these ideas [2]. Here as a further test we vary J (as measured by two-magnon Raman scattering) by more than 60% by changing ion sizes in the model HTS system LnA2Cu3O7-{\delta} where A=(Ba,Sr) and Ln=(La, Nd, Sm, Eu, Gd, Dy, Yb, Lu). Such changes are often referred to as "internal" pressure. Surprisingly, we find Tcmax anticorrelates with J where internal pressure is the implicit variable. This is the opposite to the effect of external pressure and suggests that J is not the dominant energy scale governing Tcmax.