Anisotropic non-split zero-energy vortex bound states in a conventional superconductor

Vortices in topological superconductors are predicted to host Majorana bound states (MBSs) as exotic quasiparticles. In recent experiments, the spatially non-split zero-energy vortex state has been regarded an essential spectroscopic signature for observation of MBSs. Here, we report anisotropic a conventional elemental superconductor with topologically trivial band structure using scanning tunneling microscopy and spectroscopy. The experimental results, corroborated by quasi-classical theoretical calculations, indicate that directly reflect quasiparticle trajectories governed surface electronic structure. Our study implies not conclusive MBSs cores, particular superconducting systems being quantum limit, stimulating revision current understanding such states.