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HL: Fachverband Halbleiterphysik

HL 14: 2D Materials III (joint session HL/CPP)

HL 14.3: Vortrag

Dienstag, 28. März 2023, 10:00–10:15, POT 81

Quantum Hall measurements near electric field controlled Lifshitz transitions in trigonally warped bilayer graphene — •Martin Statz, Anna Seiler, Jonas Pöhls, Moritz Knaak, Francesca Farlorsi, and Thomas Weitz — 1st Physical Institute, Faculty of Physics, University of Göttingen, Friedrich-Hund-Platz 1, Göttingen 37077, Germany

Various spontaneous symmetry broken phases such as Stoner ferromagnetism, spin-polarized superconductivity, a quantum anomalous Hall octet and a topologically non-trivial Wigner-Hall crystal phase have recently been reported in bilayer graphene (BLG) [1]. Since these interaction-driven phenomena are dictated by the ratio of the Coulomb and kinetic energy of carriers, they can be promoted by the formation of flat bands and a divergent density of states (DoS) near Lifshitz transitions (LT). Trigonally warped BLG at low vertical displacement fields (D-field) and carrier densities (∼ 10¹¹ cm⁻²) displays one centre and three off-centre Dirac cones in each valley, and therefore offers a rich playground for correlated phases (CP) and changes in the Fermi surface topology by inducing charge density and D-field driven LT. Here, we report on quantum Hall measurements near charge density and D-field driven LT in trigonally warped BLG encapsulated in hexagonal boron-nitride in a dual-gated architecture with graphite contacts and graphite gates at 10 mK. We further outline our status on the temperature dependence of several CP in the aforementioned regimes.

[1] Seiler, A.M. et al. Nature 608, 298-302 (2022)