Developing fractional quantum Hall states at even-denominator fillings 1/6 and 1/8

Abstract

In the extreme quantum limit, when the Landau level filling factor $\nu <1$, the dominant electron-electron interaction in low-disorder two-dimensional electron systems leads to exotic many-body phases. The ground states at even-denominator $\nu =$ 1/2 and 1/4 are typically Fermi seas of composite fermions carrying two and four flux quanta, surrounded by the Jain fractional quantum Hall states (FQHSs) at odd-denominator fillings $\nu =p/(2p\pm 1)$ and $\nu =p/(4p\pm 1)$, where $p$ is an integer. For $\nu <$ 1/5, an insulating behavior, which is generally believed to signal the formation of a pinned Wigner crystal, is seen. Our experiments on ultrahigh-quality, dilute, GaAs two-dimensional electron systems reveal developing FQHSs at $\nu =p/(6p\pm 1)$ and $\nu =p/(8p\pm 1)$, manifested by magnetoresistance minima superimposed on the insulating background. In stark contrast to $\nu =$ 1/2 and 1/4, however, we observe a pronounced, sharp minimum in magnetoresistance at $\nu =$ 1/6 and a somewhat weaker minimum at $\nu =$ 1/8, suggesting developing FQHSs, likely stabilized by the pairing of composite fermions that carry six and eight flux quanta. Our results signal the unexpected entry, in ultrahigh-quality samples, of FQHSs at even-denominator fillings 1/6 and 1/8, which are likely to harbor non-Abelian anyon excitations.

7+20 pages, 3+14 figures

References in corpus (13)

• Non-Abelian Anyons and Topological Quantum Computation
• Fractional statistics in anyon collisions
• Melting of a 2D Quantum Electron Solid in High Magnetic Field
• Observation of a Fractional Quantum Hall State at $\nu =1/4$ in a Wide GaAs Quantum Well
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• Composite-fermion pairing at half and quarter filled lowest Landau level
• Topological phase transition between composite-fermion and Pfaffian daughter states near ν = 1/2 FQHS
• Correlated states of 2D electrons near the Landau level filling $\nu =1/7$
• Signatures of correlated defects in an ultra-clean Wigner crystal in the extreme quantum limit
• Quantum bubble defects in the lowest Landau level crystal

Cited by in corpus (8)

• Competing Many-Body Phases at Small Fillings in Ultrahigh-Quality GaAs 2D Hole Systems: Role of Landau Level Mixing
• Dispersion of neutral collective modes in partonic fractional quantum Hall states and its applications to paired states of composite fermions
• Extreme disorder in crystalline perovskite oxide: a new paradigm in quantum materials research
• Interplay of superconducting, metallic, and crystalline states of composite fermions at $\nu =1/6$ in wide quantum wells
• Interlayer-correlated fractional quantum Hall state in a trilayer electron system
• Cascade of fractional quantum Hall states in 2D system
• Time-dependent conserved operators for autonomous systems and quantization of resistance
• Disorder-induced strong-field strong-localization in 2D systems