Competing charge density waves probed by non-linear transport and noise in the second and third Landau levels

Competing quantum ground states are ubiquitous in strongly-interacting many-body systems. One prime example is the competition between Wigner crystallization and fractional quantum Hall (FQH) liquids that occurs deep in the first Landau level (LL) of the two-dimensional electron gas (2DEG). In higher LLs, the situation is much more complex, where charge density waves (CDWs) in the form of stripe and bubble phases are also competing with incompressible FQH liquids. In this talk, I will present our results [1] concerning the competition of CDWs and FQH in the second and third LL of an ultra-high mobility GaAs/AlGaAs 2DEG, as probed by both non-linear electronic transport and noise measurements. These measurements were performed in a Corbino geometry to ensure that only bulk properties of the 2DEG were probed, thereby precluding any contribution coming from edge states. Sliding transport of CDWs was revealed by narrow-band noise in re-entrant quantum Hall states of the second LL identified by the Csathy group [2], as well as in pinned CDWs of the third LL. The combining of noise data with maps of conductivity versus magnetic field and bias voltage revealed a complex competition occurring between various quantum phases in the form of stripes, pinned CDWs and fractional quantum Hall liquids, and is consistent with recent results from the Manfra group for the stripe phase suggesting a transition between a smectic and nematic phase at finite temperatures [3].

[1] K. Bennaceur, C. Lupien, B. Reulet, G. Gervais, L. N. Pfeiffer and K. W. West, Phys. Rev. Lett. 120, 136801 (2018).
[2] N. Deng, A. Kumar, M. J. Manfra, L. N. Pfeiffer, K. W. West, G. A. Csathy, Phys. Rev. Lett. 108, 086803 (2012).
[3] Q. Qian, J. Nakamura, S. Fallahi, G. C. Gardner, and M. J. Manfra, Nat. Comm. 8, 1536 (2017).