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arXiv 2602.09526cond-mat.mes-hallcond-mat.mtrl-sci
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WS₂/WSe₂异层异质结中莫尔势的起源:来自晶格重构和层间电荷转移的贡献

Origin of Moiré Potentials in WS$_2$/WSe$_2$ Heterobilayers: Contributions from Lattice Reconstruction and Interlayer Charge Transfer

School of Physics and Electronics, Hunan University(湖南大学物理与电子学院)

Youwen Wang, Nanya Gao, Qingjun Tong

AI总结:

研究揭示了WS₂/WSe₂异质结中莫尔势的起源,通过晶格重构和层间电荷转移共同作用形成莫尔势,促进强相关效应。

摘要:

在WS₂/WSe₂异层异质结中形成的莫尔超晶格已成为探索量子多体物理的令人兴奋的平台。关键机制是通过层间相互作用的横向调制引入莫尔势,以捕获带边缘载流子。这种捕获势导致形成平坦带,增强了强相关效应。然而,对这种奇特势能的起源仍缺乏全面理解。在本文中,我们对WS₂/WSe₂异质结中形成的R型和H型莫尔图案中的莫尔势的起源进行了全面研究。我们表明,晶格重构和层间电荷转移都显著贡献于莫尔势的形成。特别是,晶格重构诱导了非均匀的局部应变,这在WS₂层的导带边缘态上产生了200 meV的能量调制,在WSe₂层的价带边缘态上产生了20 meV的能量调制。此外,晶格重构还引入了压电势能,其幅度根据堆叠和带边缘载流子的不同而从40 meV到90 meV变化。层间电荷转移诱导了内建电场,导致R型莫尔的能调制为80 meV,H型莫尔的能调制为40 meV。考虑到晶格重构和层间电荷转移的两种效应,R型和H型莫尔的形成得到了充分理解。这种捕获势将导带和价带的波函数局域在R型莫尔的同一莫尔位点,而在H型莫尔的不同莫尔位点。

英文摘要:

Moiré superlattices formed in WS$_2$/WSe$_2$ heterobilayers have emerged as an exciting platform to explore the quantum many-body physics. The key mechanism is the introduction of moiré potentials for the band-edge carriers induced by the lateral modulation of interlayer interactions. This trapping potential results in the formation of flat bands, which enhances the strong correlation effect. However, a full understanding of the origin of this intriguing potential remains elusive. In this paper, we present a comprehensive investigation of the origin of moiré potentials in both R-type and H-type moiré patterns formed in WS$_2$/WSe$_2$ heterobilayers. We show that both lattice reconstruction and interlayer charge transfer contribute significantly to the formation of moiré potentials. In particular, the lattice reconstruction induces a nonuniform local strain, which creates an energy modulation of 200 meV for the conduction band-edge state located at WS$_2$ layer and 20 meV for the valence band-edge state located at WSe$_2$ layer. In addition, the lattice reconstruction also introduces a piezopotential energy, whose amplitude ranges from 40 meV to 90 meV depending on the stacking and band-edge carrier. The interlayer charge transfer induces a built-in electric field, resulting in an energy modulation of 80 meV for an R-type moiré and 40 meV for an H-type moiré. Taking into account both effects from lattice reconstruction and interlayer charge transfer, the formation of moiré potential is well understood for both R-type and H-type moirés. This trapping potential localizes the wavefunctions of conduction and valence bands around the same moiré site for an R-type moiré, while around different moiré site for an H-type one.

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