Melted discommensuration of charge density waves

We investigate the charge density wave transport on the quasi one-dimensional system, orthorhombic tantalum trisulfide (o-TaS3), by applying a radio-frequency ac voltage. New ac–dc interference spectrum is observed in the differential conductance, which appears at both sides of the zero-bias peak. The frequency and amplitude dependences of the new spectrum do not correspond to those of any conventional ac–dc interference spectrum, namely integer and fractional Shapiro steps. The results suggest that there are unconventional internal degrees of freedom in the CDW. We propose that randomly distributed 2π2π phase solitons contribute electrical conduction when both ac and dc voltages are applied. Our results provide a new insight for a general understanding of CDW dynamics.