Octupolar Weyl superconductivity from electron-electron interaction

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Matter

Background:

• Weyl topological superconductivity (TSC) is an exotic state with protected nodes and Fermi arcs.
• Realizing Weyl TSC is challenging, often needing complex band structures or fine-tuned spin-orbit coupling.

Purpose of the Study:

• To propose a universal and robust mechanism for generating Weyl TSC.
• To explore the role of 3D cubic lattice symmetry and electron-electron interactions in realizing Weyl TSC.

Main Methods:

• Group theory and Ginzburg-Landau analysis to generalize [Formula: see text]-wave pairing to 3D cubic lattices.
• Weak-coupling (random-phase approximation) and strong-coupling (slave-boson mean-field, variational Monte Carlo) approaches.
• Utilized the single-orbital cubic Hubbard model as a prototype.

Main Results:

• A chiral [Formula: see text] state emerges from generalizing [Formula: see text]-wave pairing in a 3D cubic lattice.
• Cooper pairs develop an octupolar orbital angular momentum (OAM) component, not a net OAM.
• Eight nodal points with alternating monopole charges emerge, forming an octupolar Weyl TSC with non-trivial topology.

Conclusions:

• The study confirms the emergence of [Formula: see text] Weyl TSC via an interaction-driven, symmetry-protected mechanism.
• This mechanism simplifies the search for Weyl TSC.
• Potential realization in cubic-lattice correlated superconductors and cold-atom simulations is suggested.