Ferromagnetism Due to Spontaneous Symmetry Breaking in a Twisted Bilayer Graphene Nanoflex

Twisted bilayer graphene exhibits many intriguing behaviors ranging from superconductivity to anomalous Hall effect to ferromagnetism at a magic angle close to 1^o. In this talk, I will demonstrate ferromagnetism in a twisted bilayer graphene nanoflex (TBGNF) arising from spontaneous symmetry breaking. A first-principles density functional theory that does not make any assumption of the electronic structure is used to study the zero-dimensional twisted nanoflex. Our result shows that when the energy gap of a TBGNF approaches zero, electronic instability-induced spontaneous reorganization of electrons leads to the emergence of a stable ferromagnetic gap state with p-orbitals at the boundary of the nanoflex contributing to ferromagnetism [1].<br/><br/>[1] D. Pant, S. Aryal, S. Mandal, and R. Pati, Nano Lett. 2021, <b>21</b>, 7548-7554.