Theory of Ising superconductivity in bulk misfit heterostructures

It has recently become clear the notion that Ising superconductivity can only occur in two dimensional materials is incomplete. A key signature of Ising superconductivity is their resilience to in-plane magnetic fields that greatly exceeds the Pauli limit. Several experiments have shown in-plane thermodynamic critical fields in a class of bulk materials known as misfit layer compounds that greatly exceeds the Pauli limit. We use first-principles calculations to show the combination broken inversion symmetry, large charge transfer doping and the protection of Ising spin orbit coupling in the bulk misfit compounds contains the necessary ingredients to be classified as Ising superconductors. The results of these calculations will be discussed in the context of experiments conducted on LaSe/NbSe₂ bulk misfit heterostructures where signatures of Ising superconductivity have been reported.