Magnetic Field Dependence of the Level Spacing of a Small Electron Droplet

Abstract

The temperature dependence of conductance resonances is used to measure the evolution with the magnetic field of the average level spacing $\Delta \epsilon$ of a droplet containing $\sim 30$ electrons created by lateral confinement of a two-dimensional electron gas in GaAs. $\Delta \epsilon$ becomes very small ($<30\mu$eV) near two critical magnetic fields at which the symmetry of the droplet changes and these decreases of $\Delta \epsilon$ are predicted by Hartree-Fock (HF) for charge excitations. Between the two critical fields, however, the largest measured $\Delta \epsilon =100\mu$eV is an order of magnitude smaller than predicted by HF but comparable to the Zeeman splitting at this field, which suggests that the spin degrees of freedom are important. PACS: 73.20.Dx, 73.20.Mf

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References in corpus (6)

• Sharp and Smooth Boundaries of Quantum Hall Liquids
• Quantum Dots in Strong Magnetic Fields: Stability Criteria for the Maximum Density Droplet
• Composite Fermions in Quantum Dots
• Selection Rules for Transport Excitation Spectroscopy of Few-Electron Quantum Dots
• Low-lying excitations of Quantum Hall Droplets
• Composite Fermion Description of Correlated Electrons in Quantum Dots: Low Zeeman Energy Limit

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• Wigner Crystalline Edges in nu < 1 Quantum Dots
• Exactly Soluble Model for Umklapp Scattering at Quantum-Hall Edges
• Quantum dots in magnetic fields: thermal response of broken symmetry phases
• Conductance oscillations in tunnel-coupled quantum dots in the quantum Hall regime