Type-II Dirac Fermions in Monolayer In2O: Interplay of Magnetotransport, Spin Hall Effect, and Superconductivity.

Topological quasiparticle excited states, magnetotransport, spin Hall effect, and superconductivity in solid-state materials have consistently been the four key issues in condensed matter physics. In this work, we theoretically demonstrate that monolayer In 2 O ${\rm In}_2{\rm O}$ provides an effective platform to explore these intertwined phenomena through its unique electronic topology. First-principles calculations reveal a type-II Dirac point near the Fermi level of the electronic band structure of monolayer In 2 O ${\rm In}_2{\rm O}$ , which is split into two pairs of Weyl points with topological charges of ± 1 $\pm 1$ in the presence of spin-orbit coupling. Robust edge states along the (100) direction confirm its topologically nontrivial nature. Remarkably, the system exhibits negative magnetoresistance below the temperature of 30 K with a significant Hall conductance and a predicted superconducting transition at 1.5 K, which are induced both by phonon softening and van Hove singularities. These theoretical findings establish the monolayer In 2 O ${\rm In}_2{\rm O}$ as a prototypical two-dimensional material for investigating type-II Dirac physics and the interplay of topological states, magnetotransport, and superconductivity.