d-wave superconductivity in quintuple-layer bulk superconductor La 6 Ni 5 O 12
Researchers used a five-layer Hubbard model and variational Monte Carlo calculations to study La6Ni5O12, a bulk superconductor. The study found that a spin-singlet d_{x^2-y^2}-wave pairing state is favored, while extended s-wave pairing is strongly suppressed. This state is consistent with experimental signatures like a V-shaped density of states and specific NMR relaxation rates, suggesting La6Ni5O12 has a clean nodal superconductor with d-wave symmetry.