Abstract-Visualization of a nonlinear conducting path in an organic molecular ferroelectric by using emission of terahertz radiation

M. Sotome, N. Kida, Y. Kinoshita, H. Yamakawa, T. Miyamoto, H. Mori, and H. Okamoto

https://journals.aps.org/prb/accepted/ba073K50P1a1e407c148870869f209b1cf6800e4b

A nonlinear electric transport and switching to a negative resistance state is one of typical electric-field-induced phenomena in correlated electron materials, while their mechanisms are generally difficult to solve. In the present study, we apply the terahertz-radiation imaging method to an organic ferroelectric, α-(BEDT-TTF)2I3 [BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene] and investigate the nature of its negative resistance phenomenon. When the negative resistance state is produced, the ferroelectric order is melted in an elongated region with the width of ∼100 μm and that region grows along the direction inclined by about 40° from the b axis with the increase of nonlinear current. A comparison of the terahertz radiation intensity with the current magnitude revealed that the melted region forms a conducting path. We interpreted the diagonal growth of the conduction path by taking into account the anisotropy of the intermolecular transfer integrals.