Robust Quantum Hall Ferromagnetism near a Gate-Tuned ν = 1 Landau Level Crossing

Abstract

In a low-disorder two-dimensional electron system, when two Landau levels of opposite spin or pseudospin cross at the Fermi level, the dominance of the exchange energy can lead to a ferromagnetic, quantum Hall ground state whose gap is determined by the exchange energy and has skyrmions as its excitations. This is normally achieved via applying either hydrostatic pressure or uniaxial strain. We study here a very high-quality, low-density, two-dimensional hole system, confined to a 30-nm-wide (001) GaAs quantum well, in which the two lowest-energy Landau levels can be gate tuned to cross at and near filling factor $\nu =1$. As we tune the field position of the crossing from one side of $\nu =1$ to the other by changing the hole density, the energy gap for the quantum Hall state at $\nu =1$ remains exceptionally large, and only shows a small dip near the crossing. The gap overall follows a $\sqrt{B}$ dependence, expected for the exchange energy. Our data are consistent with a robust quantum Hall ferromagnet as the ground state.

arXiv comment7+2 pages, 4+4 figures

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Cited by in corpus (8)

• Fractional Quantum Hall State at Filling Factor $\nu =1/4$ in Ultra-High-Quality GaAs 2D Hole Systems
• Spin-selective strong light-matter coupling in a 2D hole gas-microcavity system
• Highly-Anisotropic Even-Denominator Fractional Quantum Hall State in an Orbitally-Coupled Half-Filled Landau Level
• Ultraclean two-dimensional hole systems with mobilities exceeding 10${}^7$ cm${}^2$/Vs
• Competing Many-Body Phases at Small Fillings in Ultrahigh-Quality GaAs 2D Hole Systems: Role of Landau Level Mixing
• Pseudospin Polarization of Composite Fermions under Uniaxial Strain
• Even-denominator fractional quantum Hall states with spontaneously broken rotational symmetry
• Spontaneous Breaking of the SU(3) Flavor Symmetry in a Quantum Hall Valley Nematic