Pressure-induced magnetic transition and volume collapse in FeAs superconductors: An orbital-selective Mott scenario

TL;DR

This paper proposes an orbital-selective Mott transition scenario to explain pressure-induced magnetic suppression, volume collapse, and resistivity changes in FeAs superconductors, highlighting the role of local moments and lattice coupling.

Contribution

It introduces a novel orbital-selective Mott transition framework to describe pressure-driven phase changes in FeAs superconductors, incorporating lattice effects and local-moment physics.

Findings

Pressure induces a first-order orbital-selective Mott transition.

Magnetism disappears and volume collapses at high pressure.

Superconductivity may be stabilized in the high-pressure phase.

Abstract

Motivated by pressure experiments on FeAs-122 superconductors, we propose a scenario based on local-moment physics to explain the simultaneous disappearance of magnetism, reduction of the unit cell volume, and decrease in resistivity. In this scenario, the low-pressure magnetic phase derives from Fe moments, which become screened in the paramagnetic high-pressure phase. The quantum phase transition can be described as an orbital-selective Mott transition, which is rendered first order by coupling to the lattice, in analogy to a Kondo volume collapse. Spin-fluctuation driven superconductivity competes with antiferromagnetism and may be stabilized at low temperatures in the high-pressure phase. The ideas are illustrated by a suitable mean-field analysis of an Anderson lattice model.