Noise and thermal depinning of Wigner crystals

We examine changes in the depinning threshold and conduction noise fluctuations for driven Wigner crystals in the presence of quenched disorder. At low temperatures there is a well defined depinning threshold and a strong peak in the noise power with 1/fnoise characteristics. At higher temperatures, the depinning threshold shifts to lower drives and the noise, which is also reduced in power, becomes more white in character. At lower temperatures, a washboard frequency appears when the system depins elastically or forms a moving smectic state; however, this washboard signal is strongly reduced for higher temperatures and completely disappears above the melting temperature of a system without quenched disorder. Our results are in good agreement with recent transport and noise studies for systems where electron crystal depinning is believed to arise, and also show how noise can be used to distinguish between crystal, glass, and liquid phases.

Automated summary

We investigated the effects of quenched disorder on driven Wigner crystals and found that at low temperatures, there is a clear depinning threshold and a peak in the noise power with 1/f noise characteristics. As the temperature increases, the depinning threshold shifts to lower drives and the noise power decreases, resulting in a more white noise character. Additionally, the washboard frequency signal, observed when the system depins elastically or forms a moving smectic state, is significantly reduced at higher temperatures and disappears above the melting temperature of a system without quenched disorder. Our results are consistent with recent studies on transport and noise in electron crystal depinning and demonstrate how noise can be used to distinguish between different phases.