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arXiv · 2603.15140

Moiré Ferroelectricity-Driven Band Engineering in Twisted Square Bilayers

Kejie Bao·Rui Shi·Huan Wang·Linghao Huang·Jing Wang
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Abstract

We develop the moiré band theory for M-valley twisted square homobilayers with layer groups $P$-$42m$ and $P$-$4m2$, and propose candidate material realizations. We show that moiré ferroelectricity-originating from sliding ferroelectricity in the untwisted bilayers-provides an independent control knob for miniband engineering in addition to interlayer tunneling. The competition between these two effects enables controlled switching between layer-resolved bilayer minibands and an effective single isolated miniband. Remarkably, these systems exhibit an emergent momentum-space nonsymmorphic symmetry in the absence of external magnetic fields. Large-scale \emph{ab initio} calculations identify Cu$_2$WS$_4$ and GeCl$_2$ as representative materials realizing the ferroelectricity- and tunneling-dominated regimes, respectively. Our results establish twisted square homobilayers as a promising platform for correlated band engineering beyond moiré hexagonal systems.

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Kejie Bao, Rui Shi, Huan Wang, Linghao Huang, Jing Wang. 2026-03-16. Moiré Ferroelectricity-Driven Band Engineering in Twisted Square Bilayers. https://arxiv.org/abs/2603.15140

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