Partial Dissolution of Charge Order Phase Observed in -(BEDT-TTF) 2 PF 6 Single Crystal Field Effect Transistor

The effect of an applied gate electric field on the charge-order phase in beta-(BEDT-TTF)(2)PF6 single-crystal field-effect transistor structure was observed at around room temperature by technical improvement with respect to sample preparation and electrical measurements. A relatively slight but systematic increase of the electrical conductance induced by the applied gate electric field and its temperature dependence was observed at around the metal-insulator transition temperature (T-MI). The temperature dependence of the modulated electrical conductance demonstrated that T-MI was shifted toward the lower side by application of a gate electric field, which corresponds to partial dissolution of the charge-order phase. The thickness of the partially dissolved charge order region was estimated to be several score times larger than the charge accumulation region.