Nonlinear electrical transport inλ−(BEDT−TSF)2FeCl4

Abstract

We study the current-voltage (I-V) characteristics in a quasi-two-dimensional, -d coupled organic conductor -(BEDT-TSF) 2 FeCl 4 which undergoes a metal-to-insulator transition associated with an antiferromagnetic ordering at T MI ϭ8.3 K. Drastic nonlinear transport phenomena are observed in the I-V curve, revealing a so-called negative resistance effect at an applied electric field or a current density higher than threshold E T or J T . The overall I-V curves are quite well explained phenomenologically by a nonlinear equation for a positive feedback system that the nonlinear conductivity proportional to J n with nϭ1.4(Ϯ0.1). This indicates that some carrier decondensation mechanism works in the present antiferromagnetic insulator. Discussions are presented by following quite similar nonlinear phenomena observed in a variety of quasi-one-dimensional, mixed-stack, and segregated-stack, organic insulators.

Antiferromagnetic Insulating Ground State of Molecular π-d System Λ-(BETS)2FeCl4 (BETS = Bis(ethylenedithio)tetraselenafulvalene): A Theoretical and Experimental Review

“…Below the MI transition, the resistance gradually increases with decreasing temperature. The same kind of behavior was also observed by Toyota et al and Sugiura et al [27,38]. These results suggest that the π-electrons are not fully localized below the MI transition.…”

“…We point out that the huge change of the high-frequency response within the AFI phase, the colossal magnetodielectricity, and nonlinear transport should be considered more seriously [12,38,39]. As shown in Figure 2a, we observed kink structures in the resistance below T N (MI transition).…”

“…Related to those experiments in the PM phase, I-V characteristic in the AFI state was investigated by Toyota et al [38]. A drastic non-linear transport phenomenon, known as the negative resistance effect, was observed in the I-V curve, which indicates that some carrier decondensation occurs by applying electric field.…”

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

“…[611][612][613]902,917 The initial notable finding is the !-(BETS) 2 GaCl 4 with a superconducting transition at 8 K (mid-point 5.5 K) and the !-(BETS) 2 FeCl 4 (5) with a coupled antiferromagnetic and metal-insulator transitions at 8.3 K. For the FeCl 4 salt, a relaxor ferroelectric behavior in the metallic state below 70 K 918 and a firm nonlinear electrical transport associated with the negative resistance effect in the magnetic ordered state have been observed. 919 Moreover, it has been found by Uji et al that the FeCl 4 salt shows the field-induced superconducting transition under a magnetic field of 18-41 T applied exactly parallel to the conducting layers. 610 Interestingly, the !-(BETS) 2 Fe x Ga 1Àx X 4 passes through a superconducting to insulating transition on cooling.…”

Multifunctional interplay among the conductivity, magnetism and dielectricity in π–d interacting λ-(BETS)2FeCl4

“…Let us turn back to the AFMI ground state again, in which currentevoltage (JeE) characteristics along the c axis are studied [73,74]. Fig.…”