2025/12/03 by Edmund Bell, Bell, E., K. W. Baldwin +7
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum and electron transport phenomena #Semiconductor Quantum Structures and Devices #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2512.04050
openalex publication_date 2025/12/03 · openalex created_date 2025/12/05 · openalex updated_date 2026/07/28
Two-component fractional quantum Hall (2C-FQH) states in electron bilayers have been known for decades, yet their experimental realization remained limited to low-order fractions. Here we report on several families of high-order 2C-FQH states that emerge when an in-plane magnetic field drives a controlled monolayer-to-bilayer transition in an ultra-high-mobility GaAs quantum well. These families of states proliferate symmetrically toward the filling factor ν= 1, from both ν= 2/3 and ν= 4/3, thereby respecting particle-hole symmetry. Surprisingly, many unbalanced states (with unequal layer fillings) are more robust than their parent balanced states, defying the expected hierarchy of Jain sequences. Our findings substantially expand the known landscape of 2C-FQH states, highlighting the unexpected richness of the bilayer quantum Hall regime and opening new routes for probing the interplay of symmetry, topology, and interactions in quantum Hall systems.