Interlayer coupling driven stabilization and superconductivity in bilayer CoTe2
Abstract
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 CoTe2 remains unclear. Here, using first-principles calculations, we systematically investigate monolayer and bilayer CoTe2 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 CoTe2 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 CoTe2 are primarily attributed to interlayer-coupling-induced Te-pz charge redistribution and the associated modification of the Fermi surface and electron-phonon coupling. Finally, we discuss how spin-orbit coupling in bilayer CoTe2 weakens the EPC and superconductivity. Our work clarifies how interlayer coupling can jointly tune structural stability and superconductivity in few-layer CoTe2, providing insights for engineering quantum phases in layered transition-metal dichalcogenides.
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