Séminaire de Sonia Haddad

Jeudi 10 février, 14h00 (en distanciel sur Microsoft Teams) (Team CY Warwick Theoretical Physics )

Twistronics versus straintronics in twisted bilayers of graphene and transition metal dichalcogenides.

Sonia HADDAD
(Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences de Tunis, Université Tunis El Manar)

Since the discovery of an intrinsic superconductivity in twisted bilayer graphene (TBLG) rotated at the so-called magic angle (MA) [1], the heterostructure of bilayer two-dimensional (2D) systems continue to be one of the hottest subjects in Condensed Matter Physics [1]. They are considered as an excellent playground to investigate the interplay between correlations, strain, twist angle, disorder, and topology.Several numerical studies have shown that the electronic properties of twisted bilayers of graphene (TBLG) and transition metal dichalcogenides (TMDs) are tunable by strain engineering of the stacking layers. In particular, the flatness of the low-energy moiré bands of the rigid and the relaxed TBLG was found to be, substantially, sensitive to the strain. However, to the best of our knowledge, there are no full analytical calculations of the strain dependence of these bands. We derive, based on the continuum model proposed by Bistritzer and MacDonald [3], the low-energy Hamiltoniansof twisted homobilayers of graphene and TMDs under strain at small twist angles. We discuss how strain could correct the twist angles and bring them closer to the magic angle휃푚=10.05of TBLG and how it may reduce the widths of the lowest-energy bands at charge neutrality of the twisted homobilayer of TMDs[4].

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