High Field Alloy, Thermoelectric, and mm Wave Studies of the Field Induced Superconducting State in λ-(BETS)

Alloy studies in the π -d organic conductor λ-(BETS) 2 Fe x Ga 1−x Cl 4 have given new insight into the nature of field induced superconductivity (FISC), since the mechanism of the FISC involves cancellation of the π − d exchange field by the external field. Alloying on the Fe x Ga 1−x site allows tuning of the exchange field, thereby influencing the FISC phase boundary. A brief review of the low temperature phases are given, and new high magnetic field thermoelectric and mm wave results that probe the low temperature ground state are presented. The discovery of magnetic field induced superconductivity in λ-(BETS) 2 FeCl 4 [1] (BETS= bis(ethylenedithio)tetraselenafulvalene) has drawn attention to the π−d electron spin exchange mechanisms At higher magnetic fields , field induced superconductivity (FISC) is stabilized in λ-(BETS) 2 FeCl 4 below 5 K between 18 and 45