1/f noise anomalies in nanoribbons of charge density wave materials

Charge density wave (CDW) as an ordered form of matter has attracted attention for many decades. Below a critical temperature (T$_{P}$), CDW materials undergo a Peierls transition and enter the CDW ground state, where the energy is minimized by a collectively pinning mechanism. Under a moderate electric field, CDWs can be depinned and they start sliding. An onset of a large broad band noise (BBN) has been observed in bulk CDW materials as a signature of this depinning process. We report low frequency conductance fluctuation (1/f noise) measurements on single nanoribbon devices of single-crystalline NbSe$_{3}$, across both Peierls transitions. In the CDW state, a non-monotonic behavior in the noise magnitude was observed when approaching the threshold electric field for depinning: while increasing voltage from the zero-bias limit, the magnitude of BBN first decreases before increasing sharply near the threshold voltage. This unusually large BBN magnitude and the non-monotonic behavior below the depinning threshold suggest some inherent instability that could be suppressed by a small bias field, and is clearly different from results from bulk materials. Transport and noise studies from individual nanoribbons of NbSe$_{3}$, Ta-doped NbSe$_{3}$ and o-TaS$_{3}$ will be presented.