Interplay between conducting and magnetic systems in the   antiferromagnetic organic superconductor $\kappa$-(BETS)$_2$FeBr$_4$
  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. 
Mark. V. Kartsovnik, Michael Kunz, Ludwig Schaidhammer, Florian   Kollmannsberger, Werner Biberacher, Natalia D. Kushch, Aki...
cond-mat.str-el cond-mat.supr-con