CMP Seminar: Unconventional superconductivity in materials with strong spin-orbit coupling

I will overview our recent work on layered superconductors where signatures of unconventional superconductivity are revealed or sometimes promoted by their response to magnetic fields. Magnetic correlations and superconductivity are usually antagonistic. However, in some situations external magnetic fields can be helpful in bringing to light new superconducting properties. An example is magnetic field induced transitions between superconducting states with different pairing symmetries as found in a heavy Fermion superconductor CeRh₂As₂, ion-intercalated MoS₂, and a layered centrosymmetric superconductor β-PdBi₂. Our tunnelling spectroscopy on β-PdBi₂ under in-plane magnetic fields revealed a transition from conventional s-wave pairing to a nodal p-wave superconducting state. We show that the transition, marked by a discontinuous change in the tunneling spectra, originates from spin polarization and spin–momentum locking due to locally broken inversion symmetry. Remarkably, signatures of this transition also appear in magnetization, indicating the formation of a novel domain structure consisting of coexisting p-wave superconducting and normal regions. These findings offer a new experimental window into how spin textures, symmetry breaking, and strong spin–orbit coupling can stabilize unconventional superconductivity and generate emergent magnetic responses in layered materials.