The evidence of bound solitons delocalization in o-TaS3 under dc bias from sum rule

The electric field dependence of the dielectric properties below 50 K along the chain direction of o-TaS3 has been investigated. Under a dc bias field exceeding the lower threshold E′T, the real part of dielectric constant ϵ1(ω) decreases possibly due to the decreasing concentration of bound solitons. We propose that the delocalization of bound solitons with the increasing applied electric field could be used to explain the reduction of ϵ1(ω) and the enhancement of the dc conductivity. This has also been confirmed by the quantitative comparison between the enhancement of the dc conductivity and the change of the dielectric spectral weight.