Multivalley two-dimensional electron system in an AlAs quantum well with mobility exceeding $2\times 10^6$ cm${}^2$V${}^{-1}$s${}^{-1}$

Abstract

Degenerate conduction-band minima, or `valleys', in materials such as Si, AlAs, graphene, and MoS${}_2$ allow them to host two-dimensional electron systems (2DESs) that can access a valley degree of freedom. These multivalley 2DESs present exciting opportunities for both pragmatic and fundamental research alike because not only are they a platform for valleytronic devices, but they also provide a tool to tune and investigate the properties of complex many-body ground states. Here, we report ultra-high quality, modulation doped AlAs quantum wells containing 2DESs that occupy two anisotropic valleys and have electron mobilities peaking at $2.4\times 10^6$ cm${}^2$V${}^{-1}$s${}^{-1}$ at a density of $2.2\times 10^{11}$ cm${}^{-2}$. This is more than an order of magnitude improvement in mobility over previous results. The unprecedented quality of our samples is demonstrated by magneto-transport data that show high-order fractional quantum Hall minima up to the Landau level filling $\nu =8/17$, and even the elusive $\nu =1/5$ quantum Hall state.

6 pages, 4 figures

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Cited by in corpus (20)

• Ultra-high quality two-dimensional electron systems
• Charge-transfer Contact to a High-Mobility Monolayer Semiconductor
• Observation of Spontaneous Ferromagnetism in a Two-Dimensional Electron System
• Observation of spontaneous valley polarization of itinerant electrons
• Anisotropic, two-dimensional, disordered Wigner solid
• Unconventional anisotropic even-denominator fractional quantum Hall state in a system with mass anisotropy
• Proximity screening greatly enhances electronic quality of graphene
• Working principles of doping-well structures for high-mobility two-dimensional electron systems
• Quantum Hall Valley Nematics
• Spatial Mapping of Local Density Variations in Two-dimensional Electron Systems Using Scanning Photoluminescence
• Density-dependent two-dimensional optimal mobility in ultra-high-quality semiconductor quantum wells
• Valley-tunable, even-denominator fractional quantum Hall state in the lowest Landau level of an anisotropic system
• Fractional quantum Hall valley ferromagnetism in the extreme quantum limit
• Valley polarization transition in a two-dimensional electron gas
• Electron spectra in double quantum wells of different shapes
• Competing Many-Body Phases at Small Fillings in Ultrahigh-Quality GaAs 2D Hole Systems: Role of Landau Level Mixing
• Developing fractional quantum Hall states at $\nu$ = $\frac{1}{7}$ and $\frac{2}{11}$ in the presence of significant Landau level mixing
• Fermi-surface topology and renormalization of bare ellipticity in an interacting anisotropic electron gas
• High transparency induced superconductivity in field effect two-dimensional electron gases in undoped InAs/AlGaSb surface quantum wells
• Impact of in-situ controlled disorder screening on fractional quantum Hall effects and composite-fermion transport