Emergence of Berry curvature dipole and nonlinear Hall effect in a novel hexagonal borophosphene allotrope

Abstract

We investigate the electronic structure, local orbital coupling, and strain-tunable nonlinear Hall response of two arsenic-substituted borophosphene-derived monolayers, As@MBP and As@AMBP, using first-principles calculations and tight-binding analysis. In the absence of spin--orbit coupling, both systems exhibit a finite Berry-curvature dipole (BCD) and a substantial nonlinear Hall conductivity, demonstrating that the nonlinear response is intrinsically driven by orbital physics and inversion-symmetry breaking. $As$ substitution opens sizable band gaps of $120~\mathrm{meV}$ in As@MBP and $90~\mathrm{meV}$ in As@AMBP, well exceeding room-temperature thermal fluctuations ($k_{\mathrm{B}}T \approx 25.9~\mathrm{meV}$). Tight-binding analysis reveals that $As$ incorporation breaks the equivalence of $B-P$ hoppings in As@MBP and induces sign reversals in key nearest-neighbor hoppings in As@AMBP, reflecting a pronounced electronic reconstruction beyond simple geometric effects. Under mechanical strain, the redistribution of Berry curvature yields a maximum BCD of $22~\mathring{\text{A}}$ in As@MBP, approximately $10$ times larger than that of unstrained structure, and induces a reversal of the BCD sign. These results establish $As$-substituted borophosphene derivatives as promising light-element platforms for mechanically switchable nonlinear transport and quantum-material applications without relying on strong spin-orbit coupling.