Interplay between conducting and magnetic systems in the antiferromagnetic organic superconductor $\kappa$-(BETS)$_2$FeBr$_4$

TL;DR

This study explores how conduction electrons and magnetic ions interact in the organic superconductor $$-(BETS)$_2$FeBr$_4$, revealing their mutual influence on superconductivity and magnetic properties through experimental observations.

Contribution

It provides new insights into the interplay between conduction and magnetic systems in an organic superconductor, highlighting their impact on superconductivity and magnetic phase behavior.

Findings

Magnetic quantum oscillations reflect coupling between charge carriers and magnetic system.

Pressure alters the magnetic phase diagram, indicating impact of conduction electrons on magnetism.

Interaction influences both low-field superconductivity and magnetic states.

Abstract

The mutual influence of the conduction electron system provided by organic donor layers and magnetic system localized in insulating layers of the molecular charge transfer salt $\kappa$-(BETS)$_2$FeBr$_4$ has been studied. It is demonstrated that besides the high-field re-entrant superconducting state, the interaction between the two systems plays important role for the low-field superconductivity. The coupling of normal-state charge carriers to the magnetic system is reflected in magnetic quantum oscillations and can be evaluated based on the angle-dependent beating behaviour of the oscillations. On the other hand, the conduction electrons have their impact on the magnetic system, which is revealed through the pressure-induced changes of the magnetic phase diagram of the material.