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In the past few years, van der Waals heterostructures have emerged as a new platform for studying frustrated magnetic systems, both in structures with layers exhibiting intrinsic magnetism, as well as "Hubbard model simulators" such as moiré transition metal dichalcogenides (TMD). I will first discuss bilayer U(1) Dirac spin liquids, with the homogenously stacked system being unstable towards spontaneous symmetry breaking. We show that adding a relative twist between the two layers softens the ordering instability, and the resulting ordered phase features a tuneable lattice of magnetic vortices. In the second part of my talk, I will present ongoing work on correlated insulating states at fractional fillings in moiré TMD bilayers, where the formation of self-organized charge lattices has been observed experimentally. We describe these ordered states and explore the possibility of spin-liquid states within a slave-rotor mean-field theory.

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Urban Seifert, Kavli Institute for Theoretical Physics
Seminar Room, old theory building
Contact: Simon Trebst