TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.13.2.040
TI  - Charge order and antiferromagnetism in twisted bilayer graphene from the variational cluster approximation
PY  - 2022/08/30
UR  - https://www.scipost.org/SciPostPhys.13.2.040
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 13
IS  - 2
SP  - 040
A1  - Pahlevanzadeh, B.
AU  - Sahebsara, P.
AU  - Sénéchal, David
AB  - We study the possibility of charge order at quarter filling and antiferromagnetism at half-filling in a tight-binding model of magic angle twisted bilayer graphene. We build on the model proposed by Kang and Vafek, relevant to a twist angle of $1.30^\circ$, and add on-site and extended density-density interactions. Applying the variational cluster approximation with an exact-diagonalization impurity solver, we find that the system is indeed a correlated (Mott) insulator at fillings $\frac14$, $\frac12$ and $\frac34$. At quarter filling, we check that the most probable charge orders do not arise, for all values of the interaction tested. At half-filling, antiferromagnetism only arises if the local repulsion $U$ is sufficiently large compared to the extended interactions, beyond what is expected from the simplest model of extended interactions.
ER  -

@Article{10.21468/SciPostPhys.13.2.040,
	title={{Charge order and antiferromagnetism in twisted bilayer graphene from the variational cluster approximation}},
	author={B. Pahlevanzadeh and  P. Sahebsara and D. Sénéchal},
	journal={SciPost Phys.},
	volume={13},
	pages={040},
	year={2022},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.13.2.040},
	url={https://scipost.org/10.21468/SciPostPhys.13.2.040},
}