Interlayer exciton condensates between second Landau level orbitals in double bilayer graphene

Abstract

We present Coulomb-drag measurements on a heterostructure comprising two Bernal-stacked bilayer graphene (BLG) sheets separated by a 2.5 nm hexagonal boron nitride (hBN) spacer in the quantum Hall (QH) regime. Using top and bottom gate control, together with an interlayer bias, we independently tune the two BLG layers into either the lowest (N = 0) or second (N = 1) Landau level (LL) orbital and probe their interlayer QH states. When both layers occupy the N = 0 orbital, we observe both interlayer exciton condensates (ECs) at integer total filling and interlayer fractional QH states, echoing the results in double monolayer graphene. In contrast to previous studies, however, when both BLG layers occupy the N = 1 orbital, we also observe quantized drag signals, signifying an interlayer exciton condensate formed between the second LLs. By tuning the layer degree of freedom, we find that this N = 1 EC state arises only when the N = 1 wavefunction in each BLG is polarized toward the hBN interface to maximize the interlayer Coulomb interaction.

References in corpus (25)

• The electronic properties of bilayer graphene
• Atomically thin boron nitride: a tunnelling barrier for graphene devices
• Strong Coulomb drag and broken symmetry in double-layer graphene
• Excitonic superfluid phase in Double Bilayer Graphene
• Quantum Hall Drag of Exciton Superfluid in Graphene
• Robust fractional quantum Hall states and continuous quantum phase transitions in a half-filled bilayer graphene Landau level
• Exciton Condensation and Perfect Coulomb Drag
• Even denominator fractional quantum Hall state in bilayer graphene
• High quality magnetotransport in graphene using the edge-free Corbino geometry
• Direct measurement of discrete valley and orbital quantum numbers in a multicomponent quantum Hall system
• Crossover between Strongly-coupled and Weakly-coupled Exciton Superfluids
• Odd- and even-denominator fractional quantum Hall states in monolayer WSe${}_2$
• Interlayer fractional quantum Hall effect in a coupled graphene double-layer
• Evidence for pairing states of composite fermions in double-layer graphene
• Valley Isospin Controlled Fractional Quantum Hall States in Bilayer Graphene
• Bilayer WSe${}_2$ as a natural platform for interlayer exciton condensates in the strong coupling limit
• Competing Fractional Quantum Hall and Electron Solid Phases in Graphene
• Tunable Electron Interactions and Fractional Quantum Hall States in Graphene
• Energy gap of the even-denominator fractional quantum Hall state in bilayer graphene
• Excitons in the Fractional Quantum Hall Effect
• Theoretical phase diagram of two-component composite fermions in double layer graphene
• Investigation of trial wavefunction approach to bilayer Quantum Hall systems
• Evidence for a Superfluid-to-solid Transition of Bilayer Excitons
• Quarter- and half-filled quantum Hall states and their topological orders revealed by daughter states in bilayer graphene
• Exciton Condensation in Quantum Hall Bilayers at Total Filling ${\nu }_T=5$