层间耦合驱动的双层CoTe₂稳定性和超导性
Interlayer coupling driven stabilization and superconductivity in bilayer CoTe$_2$
AI总结：
研究通过第一性原理计算揭示了层间耦合对双层CoTe₂结构稳定性和超导性的影响，发现其通过Te-p_z电荷重分布调控费米面和电子-声子耦合，预测临界温度约4.7K。
摘要：
层间耦合在范德瓦耳斯材料中通过调控晶格稳定性和新兴量子相起关键作用，但其对少层六方CoTe₂的影响尚不明确。本文通过第一性原理计算系统研究了单层和双层CoTe₂的电子结构、晶格动力学和电子-声子耦合，阐明了层间相互作用驱动的机制。结果表明，单层CoTe₂在低温下表现出显著的动力学不稳定，而层间耦合稳定了双层晶体结构并引发声子介导的超导性，预测临界温度约为4.7K。双层CoTe₂的稳定性和超导性主要归因于层间耦合诱导的Te-p_z电荷重分布及其对费米面和电子-声子耦合的修改。最后讨论了双层CoTe₂中自旋轨道耦合如何削弱电子-声子耦合并抑制超导性。本工作阐明了层间耦合如何共同调控少层CoTe₂的结构稳定性和超导性，为设计层状过渡金属二硫化物的量子相提供了见解。
英文摘要：
Interlayer coupling plays a critical role in van der Waals materials by governing lattice stability and emergent quantum phases, yet its impact on few-layer hexagonal CoTe$_2$ remains unclear. Here, using first-principles calculations, we systematically investigate monolayer and bilayer CoTe$_2$ with an emphasis on their electronic structures, lattice dynamics, and electron-phonon coupling, and elucidate the underlying mechanisms driven by interlayer interactions. Our results show that monolayer CoTe$_2$ exhibits pronounced dynamical instability at low temperatures, whereas interlayer coupling stabilizes the bilayer crystal structure and gives rise to phonon-mediated superconductivity with a predicted critical temperature of about $4.7$~K when spin-orbit coupling is included. The stabilization and superconductivity in bilayer CoTe$_2$ are primarily attributed to interlayer-coupling-induced Te-$p_z$ charge redistribution and the associated modification of the Fermi surface and electron-phonon coupling. Finally, we discuss how spin-orbit coupling in bilayer CoTe$_2$ weakens the EPC and superconductivity. Our work clarifies how interlayer coupling can jointly tune structural stability and superconductivity in few-layer CoTe$_2$, providing insights for engineering quantum phases in layered transition-metal dichalcogenides.
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