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TT: Fachverband Tiefe Temperaturen

TT 31: Topology: Quantum Hall Systems

TT 31.6: Vortrag

Mittwoch, 19. März 2025, 16:30–16:45, H31

Dipole Representation of Composite Fermions in Graphene’s Quantum Hall Systems — •Sonja Predin — Scientific Computing Laboratory, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia

The even-denominator fractional quantum Hall effect has been observed in graphene’s fourth Landau level (N = 3) [1]. Motivated by recent studies [2] on pairing and the nature of the ground state in this system, we extend the dipole representation of composite fermions to adapt it to graphene’s quantum Hall systems, focusing on half-filled Landau levels. We derive an effective Hamiltonian incorporating particle-hole symmetry. At the Fermi level, the energetic instability of the dipole state is driven by the interplay between topology and symmetry, pushing the system towards a critical state. While paired states are considered, our findings demonstrate that a boost-invariant state lacking well-defined pairing instabilities is energetically favorable stable state, suggesting the absence of pairing instabilities in this system.

[1] Y.Kim,A.C.Balram,T.Taniguchi,K.Watanabe,J.K.Jain, J.H.Smet,
Nat. Phys. 15, 154 (2019).

[2] A.Sharma, S.Pu, A.C.Balram, J.K.Jain, PRL 130, 126201 (2023).

[3] S.Predin, A.Knežević, M.V.Milovanović, PRB 107, 155132 (2023).

[4] S. Predin, arXiv:2408.10375.

Keywords: Composite fermions; Graphene; Fractional quantum Hall effect; Landau levels