Nodal network spin gapless semiconductor: A new frontier in spintronic quantum materials

Recent years have witnessed remarkable progress in the independent yet parallel advancements of topological materials and spin gapless semiconductors. The convergence of topological materials and spin gapless semiconductors offers compelling prospects for quantum materials science, yet realizing candidates that simultaneously exhibit spin-polarized gapless band crossings and nontrivial topology poses formidable challenges. Here, we report the identification of a simple yet ideal spin gapless semiconducting state in calcite-structured siderite FeCO 3 , wherein gapless band crossings collectively form an intricate topological nodal network spanning the Brillouin zone. Uniquely unifying spin-gapless electronic band structures with a novel topological nodal configuration, this material represents a new paradigm in spintronics. Through comprehensive symmetry analysis, high-resolution band structure mapping, and effective model construction, we elucidate the spatial distribution and dispersion characteristics of these gapless nodal configurations. Using maximally localized Wannier function-based tight-binding models, we uncover robust topological drumhead surface states emanating from the projected nodal network, which persist even under the inclusion of spin-orbit coupling. Furthermore, a systematic assessment of FeCO 3 's mechanical properties—including elastic constants, elastic anisotropy, and strain-dependent topological phase stability across a ±5% strain range—demonstrates the material's structural resilience and potential for tunability under realistic device operating conditions. This work establishes an ideal platform for the further investigation of nodal network spin gapless semiconductor physics and provides a blueprint for discovering complex topological spintronic materials.