Interlayer coupling driven stabilization and superconductivity in bilayer CoTe
arXiv:2603.22101 · doi:10.1103/l89c-t2s4
First-principles calculations show that interlayer coupling stabilizes bilayer CoTe₂, which becomes a phonon-mediated superconductor with a predicted Tc of ~4.7 K, while the monolayer is dynamically unstable.
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 CoTe remains unclear. Here, using first-principles calculations, we systematically investigate monolayer and bilayer CoTe 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 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 ~K when spin-orbit coupling is included. The stabilization and superconductivity in bilayer CoTe are primarily attributed to interlayer-coupling-induced Te- charge redistribution and the associated modification of the Fermi surface and electron-phonon coupling. Finally, we discuss how spin-orbit coupling in bilayer CoTe weakens the EPC and superconductivity. Our work clarifies how interlayer coupling can jointly tune structural stability and superconductivity in few-layer CoTe, providing insights for engineering quantum phases in layered transition-metal dichalcogenides.
9 pages, 5 figures