Hybrid Ising superconductor-ferromagnetic insulator heterostructures provide a unique opportunity to explore the interplay between proximity-induced magnetism, spin-orbit coupling, and superconductivity. Here we use a combination of first-principles calculations of NbSe2/CrBr3 heterostructures and an analytical theory of Ising superconductivity to analyze the existing experiments and provide a complete explanation of highly nontrivial and largely counterintuitive effects: an increase in the magnitude of the superconducting gap accompanied by the broadening of the tunneling peaks; hysteretic behavior of the tunneling conductance that sets in ≈2 K below Tc; and nematic symmetry breaking in the superconducting state. The microscopic reason in all three cases appears to be the interplay between the proximity-induced exchange splitting and intrinsic defects. Finally, we predict additional interesting effects that at the moment cannot be addressed experimentally: spin-filtering when tunneling across CrBr3 and tunneling "hot spots"in momentum space that are anticorrelated with regions where the spin-orbit splitting is maximum.
Bibliographical noteFunding Information:
We thank David Möckli, Jie Shan, Kin Fai Mak, and Rafael Fernandes for helpful discussions. D.W. was supported by the Office of Naval Research (ONR) through the Naval Research Laboratory's Basic Research Program. I.I.M. was supported by ONR through Grant No. N00014-20-1-2345. M.H. and M.K. acknowledge the financial support from the Israel Science Foundation, Grant No. 2665/20. Calculations by D.W. and I.I.M. were performed at the DoD Major Shared Resource Center at AFRL.
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