単層ZrBrにおける電子-フォノン結合および局所性工学エッジ状態を介した電子およびフォノニックトポロジーの相互編纂

Monolayer ZrBr combines excellent electronic and phononic transport, forming a compact platform for coupled topology. First-principles and Wannier-Green's-function calculations show symmetry-protected near-linear crossings along K-Γ-M-K without spin-orbit coupling (SOC). With SOC, a direct gap of ∼45.6 meV opens at Γ with a pronounced reorganization of Zr-4d orbital weights. The Wilson-loop evolution yields Z₂ = 1, and semi-infinite boundary spectra exhibit a gap-traversing helical edge channel, consistent with the constant-energy contour and in-plane spin winding. Phonon dispersions contain no imaginary frequencies and resolve two low-frequency softening anomalies at Γ and near (0.09,0.16,0); their progressive suppression with increasing electronic smearing indicates a Kohn-anomaly-type renormalization driven by Fermi-surface screening. Atom-projected phonon densities of states partition vibrations into a Zr-dominated low-frequency sector and a Br-dominated mid-to-high-frequency sector. The Eliashberg function α²F(ω) yields strong coupling λ = 1.26 and superconducting quasiparticle signatures with T_c = 21.67 K. Around ∼3.45 THz, boundary phonon spectra, iso-frequency contours, and sign-alternating phonon Berry curvature jointly indicate a nontrivial phonon geometric response.