Correlated States of 2D Electrons near the Landau Level Filling ν = 1 / 7

Journal Article · 10 January 2022 · Physical Review Letters

DOI: https://doi.org/10.1103/physrevlett.128.026802 · OSTI ID:1980254

Chung, Yoon Jang ^[1]; Graf, D. ^[2]; Engel, L.  W. ^[2]; Rosales, K. A. Villegas  ^[3]; Madathil, P.  T. ^[3]; Baldwin, K.  W. ^[3]; West, K.  W. ^[3]; Pfeiffer, L.  N. ^[3]; Shayegan, M.  ^[3]

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1. Princeton Univ., NJ (United States); OSTI
2. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
3. Princeton Univ., NJ (United States)

The ground state of two-dimensional electron systems (2DESs) at low Landau level filling factors ( $\nu \lesssim 1/6$) has long been a topic of interest and controversy in condensed matter. Following the recent breakthrough in the quality of ultrahigh-mobility GaAs 2DESs, we revisit this problem experimentally and investigate the impact of reduced disorder. In a GaAs 2DES sample with density $n=6.1\times {10}^{10}/{\mathrm{cm}}^2$ and mobility $\mu =25\times {10}^6{\mathrm{cm}}^2/\mathrm{V}\mathrm{s}$, we find a deep minimum in the longitudinal magnetoresistance ( $R_{xx}$) at $\nu =1/7$ when $T\simeq 104\mathrm{mK}$. There is also a clear sign of a developing minimum in $R_{xx}$ at $\nu =2/13$. While insulating phases are still predominant when $\nu \lesssim 1/6$, these minima strongly suggest the existence of fractional quantum Hall states at filling factors that comply with the Jain sequence $\nu =p/(2mp\pm 1)$ even in the very low Landau level filling limit. The magnetic-field-dependent activation energies deduced from the relation $R_{xx}\propto e^{E_A/2kT}$ corroborate this view and imply the presence of pinned Wigner solid states when $\nu \ne p/(2mp\pm 1)$. Similar results are seen in another sample with a lower density, further generalizing our observations.

• Research Organization: Princeton Univ., NJ (United States)
• Sponsoring Organization: Gordon and Betty Moore Foundation; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FG02-00ER45841
• OSTI ID: 1980254
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 2 Vol. 128; ISSN 0031-9007
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English