Ferromagnetic Fractional Quantum Hall States in a Valley-Degenerate Two-Dimensional Electron System

Abstract

We study a two-dimensional electron system where the electrons occupy two conduction band valleys with anisotropic Fermi contours and strain-tunable occupation. We observe persistent quantum Hall states at filling factors $\nu =1/3$ and 5/3 even at zero strain when the two valleys are degenerate. This is reminiscent of the quantum Hall ferromagnet formed at $\nu =1$ in the same system at zero strain. In the absence of a theory for a system with anisotropic valleys, we compare the energy gaps measured at $\nu =1/3$ and 5/3 to the available theory developed for single-valley, two-spin systems, and find that the gaps and their rates of rise with strain are much smaller than predicted.

References in corpus (7)

• Two-dimensional electrons occupying multiple valleys in AlAs
• Observation of Quantum Hall Valley Skyrmions
• The Two-flux Composite Fermion Series of Fractional Quantum Hall States in Strained Si
• Valley polarization and susceptibility of composite fermions around nu=3/2
• Density dependence of valley polarization energy for composite fermions
• Disorder and interactions in quantum Hall ferromagnets near $\nu =1$
• Spin excitation spectra of integral and fractional quantum Hall systems

Cited by in corpus (27)

• Unconventional Sequence of Fractional Quantum Hall States in Suspended Graphene
• Tunable Fractional Quantum Hall Phases in Bilayer Graphene
• Landau Level Mixing and the Fractional Quantum Hall Effect
• Fractional Quantum Hall Phase Transitions and Four-flux Composite Fermions in Graphene
• Nematic Valley Ordering in Quantum Hall Systems
• Fractional and integer quantum Hall effects in the zeroth Landau level in graphene
• Recent Experimental Progress of Fractional Quantum Hall Effect: 5/2 Filling State and Graphene
• Observation of spontaneous valley polarization of itinerant electrons
• Valley polarization assisted spin polarization in two dimensions
• Valley Degenerate 2D Electrons in the Lowest Landau Level
• Even-denominator Fractional Quantum Hall Effect at a Landau Level Crossing
• Multivalley two-dimensional electron system in an AlAs quantum well with mobility exceeding $2\times 10^6$ cm${}^2$V${}^{-1}$s${}^{-1}$
• Design rules for modulation-doped AlAs quantum wells
• Microscopic Theory of a Quantum Hall Ising Nematic: Domain Walls and Disorder
• Multi-Particle Pseudopotentials for Multi-Component Quantum Hall Systems
• Quantum Hall Valley Nematics
• Robust Quantum Hall Ferromagnetism near a Gate-Tuned ν = 1 Landau Level Crossing
• Multicomponent fractional quantum Hall states with subband and spin degrees of freedom
• Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing
• Unusual Landau Level Pinning and Correlated $\nu =1$ Quantum Hall Effect in Hole Systems Confined to Wide GaAs Quantum Wells
• Valley effects on the fractions in an ultrahigh mobility SiGe/Si/SiGe two-dimensional electron system
• Topology- and symmetry-protected domain wall conduction in quantum Hall nematics
• Fractional quantum Hall valley ferromagnetism in the extreme quantum limit
• Re-Symmetrizing the Broken Symmetry with Isotropic Hydrostatic Pressure
• Quantized heat flow in graphene quantum Hall phases: Probing the topological order
• Spin-singlet Gaffnian wave function for fractional quantum Hall systems
• Spontaneous Breaking of the SU(3) Flavor Symmetry in a Quantum Hall Valley Nematic