Dimensional crossover of soliton transport in TaS3 nanocrystals

Reduction of the sample size leads to a new phenomena through a change in system dimensionality. Progress of nanotechnology allows us to seek for such a size-driven effect of quasi-one-dimensional materials. Here we report recent studies of o-TaS3 nanocrystals. We found that the nonlinear conduction due to soliton transport in the charge-density-wave system became independent of temperature below 2 K. The observed I-V curves were classified to two kinds. One kind of the samples exhibit the standard activation formula, I∝ exp[−E0/E2], whereas other kind of the samples show a modified form, I ∝ exp[−(E0/E)2], where E0 is a constant, and E is an applied field. Since both kinds of the samples were synthesized in a same batch, it is plausible to attribute the difference of the I-V curves to that of the sample sizes. We interpreted it as the dimensional crossover of soliton transport, in the framework provided by Hatakenaka et al. They predicted the quantum nucleation possibility of the solutions Γ, which is proportional to the current, obeys a dimensionality-dependent formula, Γ ∝ exp(const./ED), where D is the system dimension. According to this, our observation suggests that the system dimension relevant to soliton transport was either D=1 or D=2, which depends on the system size.