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Condensed Matter > Strongly Correlated Electrons
Title: Importance of long-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene
(Submitted on 28 Dec 2020 (v1), last revised 28 Apr 2021 (this version, v3))
Abstract: Electron-electron interactions are intrinsically long ranged, but many models of strongly interacting electrons only take short-ranged interactions into account. Here, we present results of atomistic calculations including both long-ranged and short-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene and demonstrate that qualitatively different results are obtained when long-ranged interactions are neglected. In particular, we use Hartree theory augmented with Hubbard interactions and calculate the interacting spin susceptibility at a range of doping levels and twist angles near the magic angle to identify the dominant magnetic instabilities. At the magic angle, mostly anti-ferromagnetic order is found, while ferromagnetism dominates at other twist angles. Moreover, long-ranged interactions significantly increase the twist angle window in which strong correlation phenomena can be expected. These findings are in good agreement with available experimental data.
Submission history
From: Zachary Goodwin [view email][v1] Mon, 28 Dec 2020 21:47:10 GMT (1182kb,D)
[v2] Tue, 9 Mar 2021 20:07:24 GMT (1293kb,D)
[v3] Wed, 28 Apr 2021 18:17:11 GMT (1318kb,D)
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