Suppression of insulating state in (BETS)2FeCl4 by magnetic field

We report on the magnetotransport properties, up to 37 T, of the first organic conductor containing magnetic Fe3+ ions, λ-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The previously reported very sharp metal-insulator phase transition, which occurs at 8 K under ambient pressure, is suppressed when applying magnetic fields > 10 T. This unusual phenomenon may be connected to a field-induced ferromagnetic ordering of the Fe3+ ion moments. This could result in some kind of “evaporation” of the previously condensed carriers, into a field-restored highly conducting state (FRHCS). In this ground state, angular dependence of the magnetoresistance is observed for current flowing perpendicularly to the best-conduction c axis.