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arXiv · 1607.01463

Signatures of an annular Fermi sea

Insun Jo·Yang Liu·L. N. Pfeiffer·K. W. West·K. W. Baldwin·M. Shayegan·R. Winkler
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Abstract

We report Shubnikov-de Haas oscillations measurements revealing experimental signatures of an annular Fermi sea that develops near the energy band edge of the excited subband of two-dimensional holes confined in a wide GaAs quantum well. As we increase the hole density, when the Fermi level reaches the excited subband edge, the low-field magnetoresistance traces show a sudden emergence of new oscillations at an unexpectedly large frequency whose value does $\textit{not}$ correspond to the (negligible) density of holes in the excited subband. There is also a sharp and significant increase in zero-field resistance near this onset of subband occupation. Guided by numerical energy dispersion calculations, we associate these observations with the unusual shape of the excited subband dispersion which results in a "ring of extrema" at finite wavevectors and an annular Fermi sea. Such a dispersion and Fermi sea have long been expected from energy band calculations in systems with strong spin-orbit interaction but their experimental signatures have been elusive.

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Insun Jo, Yang Liu, L. N. Pfeiffer, K. W. West, K. W. Baldwin, M. Shayegan, R. Winkler. 2016-07-06. Signatures of an annular Fermi sea. https://doi.org/10.1103/physrevb.95.035103

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