Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 2: Nanotubes, Nanoribbons and Graphene

TT 2.11: Vortrag

Montag, 5. September 2022, 12:15–12:30, H22

Novel correlated phases near the van Hove singularity in Bernal bilayer graphene — •Anna Seiler¹, Fan Zhang², and Thomas Weitz¹ — ¹1st Physical Institute, Faculty of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²Department of Physics, University of Texas at Dallas, Richardson, TX, 75080, USA

Diverging density of states offers a unique opportunity to explore a wide variety of correlated phases in low dimensional systems. Graphene few-layers can host electric-field controlled Lifshitz transitions and concomitant van-Hove-singularities in the density of states. Here, we present the observation of experimental signatures consistent with various interaction-driven phases in trigonally warped Bernal bilayer graphene including the fractional metals of Stoner type (1-3). More prominently, we have found a Chern-insulating phase that emerges at finite densities in between two Lifshitz transitions and even survives at zero magnetic field (1). This phase is consistent with a topologically nontrivial Wigner-Hall crystalline phase, i.e., an electron crystal with a quantized Hall conductance as originally proposed at finite magnetic fields in 1989 (4). Evidently, our discovery shows that the reproducible, tunable, and simple Bernal bilayer graphene is a fertile ground for exploring new, rich, and intricating many-body physics.

[1] A. M. Seiler et al., arXiv:2111.06413 (2021)

[2] H. Zhou et al., Science 375, 774 (2022)

[3] S. C. de la Barrera et al., arXiv:2110.13907413 (2021)

[4] Z. Tešanović, F. Axel, B. I. Halperin, Phys. Rev. B 39, 8525 (1989)