Orthorhombic SrVSi2O7 as a potential magnetic second-order topological insulator with spin-polarized hinge states

Three-dimensional second-order topological insulators (3D SOTIs) have attracted considerable attention in recent years; however, realistic material realizations to date are overwhelmingly restricted to nonmagnetic systems. In this work, based on first-principles calculations, we demonstrate that bulk SrVSi 2 O 7 —an experimentally realized material with an orthorhombic crystal structure—is an intrinsic 3D ferromagnetic SOTI. We find that the nontrivial bulk band gap and the associated fractional topology are exclusively carried by the spin-up channel. For SrVSi 2 O 7 , the spin-up channel hosts a quantized fractional topological charge ( Q (2) = e /2), whereas the spin-down channel remains topologically trivial ( Q (2) = 0). Consistent with the higher-order bulk–boundary correspondence, SrVSi 2 O 7 is confirmed to host topologically protected and ultra-clean hinge states exclusively in the spin-up channel, well isolated from the bulk bands. Distinct from previously reported nonmagnetic 3D SOTIs, the hinge states in SrVSi 2 O 7 are intrinsically spin polarized, highlighting its potential as a platform for topological spintronic applications.