Electrically Tunable Flat Bands and Magnetism in Twisted Bilayer Graphene

T. M. R. Wolf, J. L. Lado, G. Blatter, O. Zilberberg

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)

Abstract

Twisted graphene bilayers provide a versatile platform to engineer metamaterials with novel emergent properties by exploiting the resulting geometric moiré superlattice. Such superlattices are known to host bulk valley currents at tiny angles (α≈0.3°) and flat bands at magic angles (α≈1°). We show that tuning the twist angle to α∗≈0.8° generates flat bands away from charge neutrality with a triangular superlattice periodicity. When doped with ±6 electrons per moiré cell, these bands are half-filled and electronic interactions produce a symmetry-broken ground state (Stoner instability) with spin-polarized regions that order ferromagnetically. Application of an interlayer electric field breaks inversion symmetry and introduces valley-dependent dispersion that quenches the magnetic order. With these results, we propose a solid-state platform that realizes electrically tunable strong correlations.
Original languageEnglish
Article number096802
Number of pages6
JournalPhysical Review Letters
Volume123
Issue number9
DOIs
Publication statusPublished - 30 Aug 2019
MoE publication typeA1 Journal article-refereed

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