Atomic stacking has recently emerged as an unexpected control parameter in two-dimensional (2D) materials. An important question is whether stacking can also serve as an independent design parameter for controlling electronic phases in three-dimensional (3D) layered crystals, whose scalability and environmental stability make them attractive for practical applications.
A research team led by Associate Professor Liang Cao at the High Magnetic Field Laboratory of the Chinese Academy of Sciences has now shown that it can. Using TaS 2 as a model system, the researchers demonstrate that coordinated interlayer sliding and intralayer atomic reconstruction can reorganize layered crystals into adaptive hetero-phase superlattices and generate distinct superconducting states without changing chemical composition or stoichiometry.
How sliding reshapes electronic states
Van der Waals (vdW) materials consist of atomically thin layers that are strongly bonded within each layer but only weakly coupled between neighboring layers. This weak interlayer coupling allows adjacent layers to slide relative to one another, introducing a structural degree of freedom absent in conventional three-dimensional (3D) crystals.
"We were inspired by advances in twistronics and slidetronics in 2D materials and hypothesized that interlayer sliding could provide a new pathway for controlling electronic states in bulk crystals. " said Cao. " The challenge was detecting structural variations at sub-nanometer scales, where the magnitude of the structural change can be comparable to experimental uncertainty."
In their earlier work, the team demonstrated that the stacking sequence can profoundly reshape electronic states. By constructing periodic interlayer-sliding superlattices in 1T-TaS 2 single crystals (named as LC-TaS 2 ), they showed that subtle variations in interlayer coupling can switch the material between a 3D band-insulating state and a 2D Mott-insulating state. The discovery helped clarify the origin of the insulating ground state in this prototypical correlated-electron material.
"We were fortunate that advanced spectroscopic measurements enabled us to resolve these ‘hidden’ structural signatures," said Professor Hai Xu of Anhui University, a collaborator. "Without sufficient sensitivity, the electronic consequences of stacking could easily have been overlooked."
How sliding builds self-adaptive superlattices
Building on these insights, the researchers uncovered an even more striking phenomenon. They found that interlayer sliding can cooperate with intralayer atomic reconstruction, a process termed two-tier sliding, to trigger layer-resolved transformations from the metastable 1T phase into the stable 1H phase.
Rather than occurring randomly, these transformations self-organize into ordered hetero-phase superlattices stabilized by interphase charge transfer. The resulting atomically sharp 1H/1T and 1H/1T/1H’ interfaces, where 1H’ denotes a 60º-rotated variant of the 1H phase, exhibit distinct superconducting transition temperatures, demonstrating that quantum states can be engineered through structural reorganization alone.
"These results show that atomic-scale sliding is far more than a structural curiosity," said Professor Yimin Xiong of Anhui University, a collaborator on this study. "It provides a fundamentally new strategy for constructing superlattice architectures and controlling emergent quantum states in layered materials."
Taken together, the two studies establish a unified framework in which interlayer sliding not only governs the evolution of electronic states, but also enables the construction of superlattice architectures. The work positions stacking sequence alongside chemical composition and stoichiometry as a fundamental design parameter for 3D quantum materials, laying the foundation for emerging concepts such as stacking engineering and sliding electronics.
About the Steady High Magnetic Field Laboratory
The research was supported by the Steady High Magnetic Field Facility (SHMFF), a national scientific infrastructure operated by the High Magnetic Field Laboratory of the Hefei Institutes of Physical Science, Chinese Academy of Sciences. SHMFF provides world-class high-magnetic-field environments and advanced characterization platforms for frontier research in condensed matter physics, materials science, chemistry, and life sciences.
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