Impurity effect on order modulations in superconducting systems with mixed singlet-triplet pairing

Based on a model Hamiltonian including the on-site repulsive interaction among the electrons, we investigate the effect induced by nonmagnetic impurities in bulk superconducting systems with mixed singlet-triplet pairing by numerically solving the Bogoliubov-de Gennes equations. For the emergent spin-triplet p-wave as well as coexisted spin-singlet s-wave and d-wave pairing symmetries, the order-parameter patterns for the quantized vortex states with point-like cores can be effectively tuned by the located sites of nonmagnetic impurities. The next-nearest-neighbor hopping effect on the evolution of vortex configurations is also discussed in the presence of vortex pinning by the impurity. Besides the unconventional vortex lattice, several types of topological defects, including the unclosed domain walls and enclosed skyrmionic modes, can be obtained when the impurity position is varied. All these configurations can be resolved by the zero-energy peaks in the local density of states.