In a groundbreaking study published in Nature, researchers have unveiled remarkable insights into the interplay of electron correlations, Mott physics, and superconductivity in a twisted bilayer system based on tungsten diselenide (tWSe₂). By precisely tuning the twist angle between two layers of WSe₂, the team has engineered a platform that transcends previous limitations, revealing a rich phase diagram near filling factor ν = 1 that strikingly mirrors the complex phenomenology observed in high-temperature cuprate superconductors. This achievement marks a significant leap forward in understanding the mechanisms underpinning exotic electronic states and offers promising avenues for unraveling one of condensed matter physics’ most profound mysteries: high-T_c superconductivity.
At the heart of this research lies the concept of moiré superlattices, where slight angular misalignments between two-dimensional crystals give rise to periodic interference patterns. These moiré patterns drastically alter the electronic band structure, enabling control over electron correlations via bandwidth modulation. Specifically, the team’s ability to tune tWSe₂ into a moderate correlation regime has facilitated the exploration of many-body physics that was previously inaccessible in transition metal dichalcogenide (TMD) systems. This capability is essential for realizing effective Hubbard model analogues, which serve as foundational frameworks for describing strong electron interactions that lead to phenomena such as Mott insulation and unconventional superconductivity.
The study carefully examines the phase behavior at electron filling ν = 1, a regime known for its sensitivity to correlation effects. By varying the twist angle—and thereby the effective bandwidth—the researchers induced a Mott metal-insulator transition akin to that observed in strongly correlated materials. Remarkably, superconductivity emerges exclusively in proximity to this Mott transition, a hallmark shared with the celebrated cuprate phase diagram. This observation lends weight to the hypothesis that strong correlations, rather than conventional phonon-mediated pairing, are central to the formation of high-T_c superconducting states.
Transport measurements conducted on twisted WSe₂ devices reveal a dome-shaped superconducting phase flanked by insulating regions, evocative of the doping-dependent phase diagrams that have long fascinated condensed matter physicists. The dome itself is sensitively tuned not only by electron doping but also by twist-angle-driven changes in bandwidth, emphasizing the dual role of carrier concentration and electron kinetic energy in orchestrating the emergent states. Such tunability underscores the versatility of moiré platforms as quantum simulators, capable of emulating key aspects of the Hubbard model that govern complex materials.
The presence of a strange metal phase adjacent to the superconducting dome further deepens the analogy with cuprates. This non-Fermi liquid regime is characterized by anomalous transport properties and is believed to be intimately linked to quantum criticality. The ability to access and systematically study this phase in a clean, controllable environment such as twisted TMDs could shed unprecedented light on the microscopic origins of quantum critical behavior and its relationship to high-temperature superconductivity.
Numerical studies of the Hubbard model have long predicted superconductivity that peaks near the Mott insulating state, governed by strong Coulomb repulsion and spin fluctuations. The current experiments in tWSe₂ provide compelling empirical support for these predictions, validating theoretical models that emphasize electron-electron interactions over conventional phonon coupling. This insight challenges traditional BCS paradigms and suggests that future research must continue exploring unconventional pairing mechanisms rooted in electronic correlations.
Despite these transformative findings, the exact nature of the superconducting order parameter in twisted WSe₂ remains to be elucidated. Probing the symmetry of the pairing state—whether d-wave, p-wave, or otherwise—requires advanced spectroscopic and thermodynamic techniques. Furthermore, identifying the microscopic interactions that stabilize superconductivity will be crucial to understanding whether the mechanism indeed mirrors that of cuprates or represents a distinct paradigm within moiré materials.
The moiré superlattice platform offers unparalleled experimental control, including the ability to adjust twist angle, carrier density, strain, and external fields. This flexibility sets the stage for systematic exploration of complex phases and transitions in a tunable solid-state simulator. By bridging nanoscale engineering with many-body phenomenology, twisted TMD systems such as tWSe₂ provide a promising experimental playground to dissect competing interactions that ultimately govern exotic ground states.
Moreover, the high degree of reproducibility and stability in WSe₂-based moiré devices mitigates complications arising from disorder and inhomogeneity, which often plague other correlated systems. This cleanliness enables high-precision measurements critical for resolving subtle signatures of electron correlation, quantum fluctuations, and pairing phenomena. Consequently, tWSe₂ devices stand poised to become benchmark platforms for benchmarking theories of unconventional superconductivity.
Looking forward, integrating complementary probes such as scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and nuclear magnetic resonance will yield deeper insights into electronic structure and dynamics. Additionally, exploring the interplay between spin, valley, and orbital degrees of freedom unique to TMDs promises to unlock novel correlated phases beyond those accessible in cuprates. The fusion of experimental advances with theoretical modeling holds great promise for a comprehensive framework of strongly correlated electron matter.
This study heralds a new era in condensed matter physics where quantum materials can be designed with atomic precision to emulate and probe formidable theoretical problems such as the Hubbard model and high-temperature superconductivity. Through the prism of twisted TMD moiré superlattices, researchers have unveiled a pathway to explore and potentially solve decades-old puzzles surrounding unconventional superconductors, bringing us closer to harnessing their intriguing properties for technological breakthroughs.
In sum, the discovery of bandwidth-tuned Mott transitions and adjacent superconductivity in tWSe₂ moiré superlattices provides compelling evidence that strong electronic correlations are indispensable for understanding high-T_c phenomena. By offering a clean, versatile, and tunable experimental system, this work establishes a powerful platform to illuminate the intertwined phases of matter that have long obstructed progress in both fundamental science and potential applications like quantum computing and lossless energy transport. The community eagerly anticipates further experimental and theoretical advances that will build on this promising foundation.
Subject of Research:
Twisted bilayer WSe₂ moiré superlattices as a platform for exploring bandwidth-controlled Mott transitions and unconventional superconductivity.
Article Title:
Bandwidth-tuned Mott transition and superconductivity in moiré WSe₂
Article References:
Xia, Y., Han, Z., Zhu, J. et al. Bandwidth-tuned Mott transition and superconductivity in moiré WSe₂. Nature (2026). https://doi.org/10.1038/s41586-025-10049-3
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