Giant nonlinear conduction in the charge ordered organic conductor θ-(BEDT-TTF)2MM'(SCN)4 (M = Cs, Rb; M' = Co, Zn) is analyzed in relation to the current-induced suppression of the charge ordered state characterized by a wave vector of q2 =(0k 1/2). On the basis of a theory of the nonequilibrium Peierls transition, the energy gap is calculated as a function of current density Jext, which is found to depend weakly on temperature in an intermediate temperature range. This justifies the evaluation of the charge-order energy gap Δ from the nonlinear resistivity ρ assuming ρ ∞ exp[Δ(Jext)/kBT], and Δ(Jext) is found to be consistent with the calculation. We compare the present results with nonequilibrium superconducting states induced by excess quasiparticles, and discuss a mechanism of current-induced suppression of the charge ordering in the title compound.
ASJC Scopus subject areas