Student Seminar | May 05, 16:30
Dirac quantum criticality in moiré materials
Moiré systems such as twisted bilayer graphene are a novel platform for the realization of strongly correlated physics and topological states of matter. We study quantum phase transitions in these materials, where the twist angle or applied pressure serve as tuning parameters.
In twisted bilayer graphene, we uncover a continuous semimetal-to-insulator quantum phase transition that belongs to the Gross-Neveu-XY universality class. Motivated by recent experimental results, we further study a twist-tuned semimetal-to-insulator transition in moiré transition metal dichalcogenides, which is shown to be continuous and belongs to the Gross-Neveu-Heisenberg universality class. The insulating ground state is antiferromagnetically ordered, with spin density modulations on the moiré scale. Intriguingly, we find that this transition can also be realized by applying pressure to the moiré system, providing a readily accessible tuning knob that may enable the first experimental observation of the universal signatures of Gross-Neveu criticality.
TU Dresden
0.03
Contact: Partha Sarker