Endowing the Ising superconductor NbSe2 with nontrivial band topology via proximity coupling with the two-dimensional ferromagnet Fe3GeTe2

Using first -principles calculations combined with the Lowdin partitioning method, we investigate the layerresolved topological properties of the Ising superconductor NbSe2 proximity coupled with a two-dimensional metallic ferromagnet Fe3GeTe2 (FGT). We first reveal that the top NbSe2 monolayer develops a nontrivial band topology under the lateral compression caused by the FGT overlayer, while the remaining NbSe2 layers maintain their band triviality. More significantly, the top NbSe2 monolayer exhibits distinctly different band topology when the FGT magnetization is switched off or on, characterized by a topological invariant Z2 = 1 or Chern number C = 1, respectively. We further confirm that the Ising pairing nature in the top NbSe2 monolayer is well preserved in the heterostructure. This study not only provides an appealing candidate system for realizing topological Ising superconductivity, but also presents a generic first -principles based approach for describing topological superconductivity beyond prevailing empirical phenomenological modeling.