Broken symmetries and excitation spectra of interacting electrons in partially filled Landau levels
Year: 2023
Type: preprint
Abstract: Interacting electrons in flat bands give rise to a variety of quantum phases. One fundamental aspect of such states is the ordering of the various flavours - such as spin or valley - that the electrons can undergo and the excitation spectrum of the broken symmetry states that they form. These properties cannot be probed directly with electrical transport measurements. The zeroth Landau level of monolayer graphene with four-fold spin-valley degeneracy is a model system for such investigations, but the nature of its broken symmetry states - particularly at partial fillings - is still not understood. Here we demonstrate a non-invasive spectroscopic technique with a scanning tunneling microscope and use it to perform measurements of the valley polarization of the electronic wavefunctions and their excitation spectrum in the partially filled zeroth Landau level of graphene. We can extract information such as the strength of Haldane pseudopotentials that characterize the repulsive interactions underlying the fractional quantum states. Our experiments also demonstrate that fractional quantum Hall phases are built upon broken symmetry states that persist at partial filling. Our experimental approach quantifies the valley phase diagram of the partially filled Landau level as a model flat band platform which is applicable to other graphene-based electronic systems.
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, Princeton Center for Complex Materials, Leverhulme Trust, Ministry of Education, Culture, Sports, Science and Technology, Office of Science, Materials Research Science and Engineering Center, Harvard University, Multidisciplinary University Research Initiative, Japan Society for the Promotion of Science, Office of Naval Research, Division of Materials Research, Basic Energy Sciences, Core Research for Evolutional Science and Technology, Army Research Office
Awards: PROBING CORRELATED SUPERCONDUCTORS AND THEIR PHASE TRANSITIONS ON THE NANOMETER SCALE, G1268236209, G1286236842, G1286251239, G1314494723, G1349703009, G1414775356, G1445641779, Princeton Center for Complex Materials, G1783960089, G1799655592, G1816284028, G1829435969, G1863003419, G1877134453, G2055624445, G222768804, G2779214953, Ali Yazdani Experimental Investigator Award, G2868987701, G30714459, G3083819904, G3224369381, G3406638862, G3510308925, G365575497, G369169853, G3715997057, G419881185, G42916606, G4501827968, G4636866504, G4703715196, G4796240486, G498139845, G5200267745, G5261056217, Visualizing quantum Hall ferromagnets, their 1D topological edge modes and their interplay with superconductivity, G5613623313, G5648016710, G5849692847, G58802512, G6004593654, G650090426, G6621819458, G6718509927, G6902702339, G6918153286, G7056553135, G7097480066, G7177903685, G7347247380, G7452299184, G7524530, PROBING CORRELATED SUPERCONDUCTORS AND THEIR PHASE TRANSITIONS ON THE NANOMETER SCALE, G7879866177, G805243471, G8387899963, G841299357, G969889393
OpenAlex ID: W4361865556