Composite fermion mass: Experimental measurements in ultrahigh quality two-dimensional electron systems
Year: 2022
Type: article
Abstract: Composite fermions (CFs), exotic quasiparticles formed by pairing an electron and an even number of magnetic flux quanta, emerge at high magnetic fields in an interacting electron system, and can explain phenomena such as the fractional quantum Hall state (FQHS) and other many-body phases. CFs possess an effective mass $({m}_{\text{CF}})$ whose magnitude is inversely related to the most fundamental property of a FQHS, namely its energy gap. We present here experimental measurements of ${m}_{\text{CF}}$ in ultrahigh quality two-dimensional electron systems confined to GaAs quantum wells of varying thickness. An advantage of measuring ${m}_{\text{CF}}$ over gap measurements is that mass values are insensitive to disorder and are therefore ideal for comparison with theoretical calculations, especially for high-order FQHS. Our data reveal that ${m}_{\text{CF}}$ increases with increasing well width, reflecting a decrease in the energy gap as the electron layer becomes thicker and the in-plane Coulomb energy softens. Comparing our measured masses with available theoretical results, we find significant quantitative discrepancies, highlighting that more rigorous and accurate calculations are needed to explain the experimental data.
Institution: Princeton University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, National High Magnetic Field Laboratory, Materials Research Science and Engineering Center, Harvard University, Division of Materials Research, Division of Electrical, Communications and Cyber Systems, Basic Energy Sciences, High Magnetic Field Laboratory, Chinese Academy of Sciences
Awards: Probing Exotic Phases of Ultra High Mobility Two-Dimensional Electrons, G1138554163, G1746067696, National High Magnetic Field Laboratory Renewal 2018-2022, G2174132073, Supplying the Quantum Materials Community with Record-Mobility Gallium Arsenide Quantum Wells, G2458691139, G3101709700, G354028113, G3560959519, G410635398, G4535154840, Electronic spin and valley degrees of freedom - based novel quantum devices, G6010147111, MAGNETO-TRANSPORT IN GAAS TWO-DIMENSIONAL HOLE SYSTEMS, G6536552022, Princeton Center for Complex Materials, G7043668614, G7214215584, G7494918340
OpenAlex ID: W4284676293