Nonlinear I-V characteristics and noise in transport in the Wigner solid regime

Two dimensional electrons in a perpendicular magnetic field at very low temperatures and Landau level fillings (v) crystallize into a Wigner solid which is typically pinned by the disorder potential. A sufficiently strong external electric field/current de-pins the solid and causes it to slide. This is reflected in the non-linear behavior of the differential resistance (dV/dI) as a function of current (I_dc),¹ along with an onset of noise and an oscillatory current whose frequency depends on I_dc.² We report non-linear I-V and noise measurements at small fillings (v < 0.2) in an ultra-low-disorder 2D electron system confined to a GaAs quantum well with a density of 2.83x10¹⁰ cm^-2 and an extremely high mobility of 15x10⁶ cm²/Vs.³ We observe complex, non-monotonic, oscillatory features in dV/dI at the onset of the sliding regime, which disappears at higher temperatures. Narrow-band noise measurements in the sliding regime reveals the presence of a characteristic frequency that varies linearly with I_dc but is ~1000 times smaller than the expected washboard frequency, suggesting filamentary conduction through the sample.

Ref:

1. V.J. Goldman et al., Phys. Rev. Lett. 65, 2189 (1990).

2. Y.P. Li et al., Solid State Commun. 96, 379 (1995).

3. Yoon Jang Chung et al., Nat. Mat. 20, 632 (2021).