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MA: Fachverband Magnetismus

MA 36: Focus Session: Ising Superconductivity in Monolayer Transition Metal Dichalcogenides (joint session TT/HL/MA)

MA 36.4: Topical Talk

Thursday, March 20, 2025, 11:15–11:45, H36

Unconventional Pairing in Ising Superconductors — •Andreas Kreisel¹, Subhojit Roy^2,3,4, Brian M. Andersen¹, and Shantanu Mukherjee^2,3,4 — ¹Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark — ²Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India — ³Center for Atomistic Modelling and Materials Design, IIT Madras, Chennai 600036, India — ⁴Quantum Centers in Diamond and Emergent Materials (QCenDiem)-Group, IIT Madras, Chennai, 600036 India

Ising spin orbit coupling arises in materials with non-centrosymmetric crystal structure in conjunction of an in-plane mirror symmetry and is realized in some two dimension transition metal dichalcogenides. Example materials are monolayer NbSe₂, MoS₂, TaS₂, and PbTe₂, where signatures of unconventional superconductivity are found in contrast to their three dimensional bulk counterparts. In this talk, I present a microscopic formalism to calculate the superconducting instability from a momentum-dependent spin- and charge-fluctuation-mediated pairing interaction in presence of spin orbit coupling that induces a spin splitting. This pairing is then applied to the electronic structure of transition metal dichalcogenides. We provide a quantitative measure of the mixing between the even- and odd-parity superconducting states which varies with Coulomb interaction. The pairing scenario from spin fluctuations together with the mixing of the odd-parity superconducting state gives rise to an enhancement of the critical magnetic field.

Keywords: NbSe$_2$; spin-fluctuation pairing; critical magnetic field