Broken-symmetry states at half-integer band fillings in twisted bilayer graphene

Bhowmik, S and Ghawri, B and Leconte, N and Appalakondaiah, S and Pandey, M and Mahapatra, PS and Lee, D and Watanabe, K and Taniguchi, T and Jung, J and Ghosh, A and Chandni, U (2022) Broken-symmetry states at half-integer band fillings in twisted bilayer graphene. In: Nature Physics .

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Abstract

The dominance of Coulomb interactions over the kinetic energy of electrons in flat moiré bands of magic-angle twisted bilayer graphene (TBG) gives rise to a variety of correlated phases, including correlated insulators1–3, superconductivity2,4,5, orbital ferromagnetism2,6, Chern insulators7–10 and nematicity11. Most of these phases occur when the carrier density is at or near an integer number of carriers per moiré unit cell. However, the demonstration of ordered states at fractional moiré band fillings at zero applied magnetic field is more challenging. Here we report the observation of states near half-integer band fillings 0.5 and ±3.5 at near-zero magnetic field in TBG proximitized by tungsten diselenide. Furthermore, at a band filling near −0.5, a symmetry-broken Chern insulator emerges at high magnetic field that is compatible with the band structure calculations within a translational symmetry-broken supercell with twice the area of the original TBG moiré cell. Our results are consistent with a spin or charge density wave ground state in TBG in the zero-magnetic-field limit. © 2022, The Author(s), under exclusive licence to Springer Nature Limited.

Item Type:	Journal Article
Publication:	Nature Physics
Publisher:	Nature Research
Additional Information:	The copyright for this article belongs to Nature Research.
Keywords:	Charge density; Charge density waves; Filling; Ground state; Kinetic energy; Kinetics; Magnetic fields; Selenium compounds; Tungsten compounds, Band fillings; Bilayer Graphene; Broken symmetry; Filling in; Integer numbers; Magic angle; Orbitals; Symmetry state; Twisted bilayers; Zero magnetic fields, Graphene
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics Division of Physical & Mathematical Sciences > Physics
Date Deposited:	18 May 2022 07:22
Last Modified:	18 May 2022 07:22
URI:	https://eprints.iisc.ac.in/id/eprint/71830

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