SciPost Submission Page
Spin-orbital magnetism in moiré Wigner molecules
by Ahmed Khalifa, Rokas Veitas, Francisco Machado, Shubhayu Chatterjee
Submission summary
| Authors (as registered SciPost users): | Ahmed Khalifa |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2507.06307v2 (pdf) |
| Date submitted: | Nov. 8, 2025, 7:25 a.m. |
| Submitted by: | Ahmed Khalifa |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
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 moir\'e 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 moir\'e 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 moir\'e Wigner molecules in TMD materials as a prominent platform for correlated spin-orbital phenomena.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Current status:
Reports on this Submission
Strengths
2 - Experimental outlook on how the model could help probing correlated phases without net magnetization (which also guides experimental works for confirmation of the presented phase diagram)
3 - Extensive Supplementary Material facilitating the understanding of each step of the work and its results, from the classical to the quantum approach, to details about the proposed ordered states (see formatting suggestions in the Report section).
4 - Flexibility of the model for various TMDs and multiple tunable parameters
Weaknesses
Report
In this work the authors propose an interesting model based on the formation of Wigner molecules in TMDs. Using the low-energy manifold of Wigner molecules, a general effective spin-orbital Hamiltonian is derived according to the symmetries of the system. Through fully-classical optimization and infinite density-matrix renormalization group, a theoretical classical and quantum phase diagram for twisted bilayer $\text{WS}_2$ is constructed, holding exotic phases such as a helical spin liquid. While Wigner molecules in TMDs were already presented in previous works, their use as a platform for spin-orbital interactions and strong correlations in TMDs is new (at least to my knowledge).
About the formatting of the work, I would suggest two things in order to better fit SciPost's style: - Scipost does not publish Supplementary Material, a simple fix would be to transform this part of the paper into Appendices - The main text lacks a clear structure, which could be fixed using sections with titles (in page 2 for example, the "Wigner molecule local Hilbert space." in italic could be used as a section "I. Wigner molecule local Hilbert space.").
Otherwise, this paper presents a robust study of TMDs and has possible ramifications for future theoretical and experimental works (see the Strengths section). Thus I strongly recommend publication.
Requested changes
1 - Few typos in the Supplemental Material:
page 14 "Hamiltonina" --> "Hamiltonian"
page 16, near the bottom "minimial"-->"minimal"
2 - Figure 5 is never directly mentioned even though its contents are tackled in the discussion in page 6 (fingerprints of the presented correlated phases and their importance for experimental works)
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)