Low-field Landau-level crossings in ABA pentalayer graphene revealed by sequential plateau disappearances

Abstract

We investigated suspended Bernal-stacked (ABA) pentalayer graphene with ultralow disorder and observed well-defined quantum Hall plateaus and Landau-level crossings at magnetic fields below 2 T. As the magnetic field increases, the initially robust plateaus at filling factors ν = −22, −18, −14, −10, and −6 successively disappear from larger |ν| at characteristic fields B* ≈ 0.26, 0.32, 0.42, 0.62, and 1.3 T, respectively, where B* denotes the first field at which a given plateau vanishes. This sequence is consistent with crossings between the Nth Landau level (N = 5, 4, 3, 2, and 1) of a monolayer-graphene-like subband and a nearly field-independent low-lying Landau level of a bilayer-graphene-like subband. A Slonczewski–Weiss–McClure tight-binding model that includes only the dominant hopping parameters γ0 and γ1, augmented by an interaction-induced staggered layer potential, quantitatively reproduces these first-disappearance fields. These results establish ABA pentalayer graphene as a tunable platform in which the interplay between the parity-dictated subband structure and electron–electron interactions governs Landau-level crossings at unusually low magnetic fields.