Low-dimensional materials host phenomena absent in bulk systems, e. g. Ising superconductivity in monolayer 1H‑NbSe₂, where spin–orbit locking allows in‑plane critical fields to exceed the Pauli limit. This form of superconductivity is particularly compelling because it creates conditions for nontrivial band topology, and potentially topological superconductivity. Yet, the instability of two‑dimensional materials presents an obstacle to applications. We demonstrate that bulk heterostructures consisting of NbSe₂ mono‑ and bilayers separated by spacer monolayers retain a two‑dimensional electronic structure and exhibit robust Ising superconductivity, with in‑plane critical fields reaching up to ten times the Pauli limit [1]. By combining structural characterization, magnetotransport experiments, and ab initio calculations, we extract key band parameters that reveal suppressed interlayer coupling and pronounced spin–orbit splitting, elucidating the microscopic origin of Ising superconductivity in bulk systems [2]. Furthermore, using the 4Ha‑NbSe₂ polytype as a model system, we show that broken inversion symmetry alone can sustain Ising protection in the bulk even in the absence of intercalation [3]. Finally, we probe the local density of states of bulk Ising superconductors using scanning tunneling microscopy.

References

1. P. Samuely et al., Phys. Rev. B 104, 224507 (2021).

2. T. Samuely et al., Phys. Rev. B 108, L220501 (2023).

3. D. Volavka et al., Phys. Rev. Lett. 136 016002 (2026).