Abstract
Type-Ⅱ Dirac semimetals exhibit a unique Fermi surface topology,which allows them to host novel topological superconductivity(TSC).We reveal a novel inter-orbital superconducting state,corresponding to the B1u and B2u pairings under the D4h point group.Intriguingly,we find that both first-and second-order TSC coexist in this novel state.It is induced by a dominant inter-orbital attraction and possesses surface helical Majorana cones and hinge Majorana flat bands,spanning the entire z-directed hinge Bril-louin zone.Further investigation uncovers that these higher-order hinge modes are robust against the C4z symmetry-breaking perturbation.
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