Giant nonlinear conduction from inhomogeneous charge order in rapidly cooled θ-(BEDT-TTF)2RbZn(SCN)4

We find a giant nonlinear conduction in the charge-ordered organic salt theta-(BEDT-TTF)(2)RbZn(SCN)(4) in a rapidly cooled state from 34 to 99 K, which cannot be ascribed to a simple Joule heating. The observed voltage-current characteristics are essentially identical to those of the related organic salt theta-(BEDT-TTF)(2)CsZn(SCN)(4), while the energy scale and the working temperatures are 1 order of magnitude higher. Considering that two kinds of charge-ordered domains coexist in this rapidly cooled state, we suggest that the inhomogeneity made of the two charge orders plays an essential role in the giant nonlinear conduction of the theta-type organic salts.