Spin-orbital magnetism in moiré Wigner molecules

Abstract

The interplay of spin and orbital degrees of freedom offers a versatile playground for the realization of a variety of correlated phases of matter. However, the types of spin-orbital interactions are often limited and challenging to tune. Here, we propose and analyze a new platform for spin-orbital interactions based upon a lattice of Wigner molecules in moiré transition metal dichalcogenides (TMDs). Leveraging the spin-orbital degeneracy of the low-energy Hilbert space of each Wigner molecule, we demonstrate that TMD materials can host a general spin-orbital Hamiltonian that is tunable via the moiré superlattice spacing and dielectric environments. We study the phase diagram for this model, revealing a rich landscape of phases driven by spin-orbital interactions, ranging from ferri-electric valence bond solids to a helical spin liquid. Our work establishes moiré Wigner molecules in TMD materials as a prominent platform for correlated spin-orbital phenomena.

v3: 12+24 pages, 5+8 figures. Submission to SciPost Physics. v2: 7+15 pages, 5+7 figures. Added further data and analysis to main text and supplemental material. v1: 6+15 pages, 4+5 figures