2021/11/30 by B. Pahlevanzadeh, Pahlevanzadeh, B., P. Sahebsara +3
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Graphene research and applications #Quantum and electron transport phenomena #Strongly Correlated Electrons (cond-mat.str-el) #Theoretical and Computational Physics
paper · pdf · doi:10.48550/arxiv.2112.00181
openalex publication_date 2021/11/30 · openalex created_date 2022/11/12 · openalex updated_date 2026/07/28
We study the possibility of charge order at quarter filling and\nantiferromagnetism at half-filling in a tight-binding model of magic angle\ntwisted bilayer graphene. We build on the model proposed by Kang and Vafek\n[Physical Review X 8(3), 031088 (2018)], relevant to a twist angle of\n1.30^\∘, and add on-site and extended density-density interactions.\nApplying the variational cluster approximation with an exact-diagonalization\nimpurity solver, we find that the system is indeed a correlated (Mott)\ninsulator at fillings frac14, frac12 and frac34. At quarter filling,\nwe check that the most probable charge orders do not arise, for all values of\nthe interaction tested. At half-filling, antiferromagnetism only arises if the\nlocal repulsion U is sufficiently large compared to the extended\ninteractions, beyond what is expected from the simplest model of extended\ninteractions.\n