The importance of local band effects for ferromagnetism in hole doped La$_2$CuO$_4$

TL;DR

This paper demonstrates that local band effects and clustering in doped La$_2$CuO$_4$ significantly influence ferromagnetism, challenging the rigid band model and suggesting a link to superconductivity suppression.

Contribution

It reveals the importance of local clustering and band effects in ferromagnetism, which are not captured by traditional averaged models like the virtual crystal approximation.

Findings

Weak ferromagnetism can occur locally around high Ba concentration clusters.

Averaged models fail to predict magnetic moments in highly doped regions.

Local effects may explain the destruction of superconductivity at high hole doping.

Abstract

Band calculations for supercells of La$_{(2-x)}$Ba$_x$CuO$_4$ show that the rigid band model for doping is less adequate than what is commonly assumed. In particular, weak ferromagnetism (FM) can appear locally around clusters of high Ba concentration. The clustering is important at large dilution and averaged models for magnetism, such as the virtual crystal approximation, are unable to stabilize magnetic moments. These results give a support to the idea that weak FM can be the cause of the destruction of superconductivity at high hole doping.