A New Platform for Spin-Polarized Majorana Zero Modes: Penta-Silicene Nanoribbons

We report the possibility of obtaining Majorana zero modes (MZMs) in straight, highly perfect, and massively aligned atom-thin penta-silicene nanoribbons (p-SiNRs) with a very high aspect ratio, purely composed of silicon pentagonal building blocks, and grown by molecular beam epitaxy on the (110) surface a silver crystal template2,3. They could constitute the experimental realization of the generic Kitaev toy model3,4. The spinless and full spin p-SiNRs with p-wave superconducting pairing reveal the emergence of topologically protected MZMs at opposite ends of the p-SiNRs. Besides the first nearest neighbor hopping term and p-wave superconducting pairing we consider an external magnetic field perpendicularly applied to the nanoribbon plane and an intrinsic Rashba spin-orbit coupling. The dispersion relation profiles show the closing and reopening of the superconducting gap for only one spin component, suggesting a spin-polarized topological phase transition (TPT). Along with this TPT, the energy spectrum as a function of the p-SiNR chemical potential exhibits zero-energy states and preferential spin direction. It is associated with nonoverlapping wave functions well-localized at the opposite extremities of the superconducting p-SiNRs. Hence, we show theoretically that the p-SiNRs could constitute a tantalizing new platform for MZMs5.<br/><br/>1. Jorge I. Cerda et al., Nature Comm., 7, 13076 (2016).<br/>2. R. Pawlak et al., PNAS, 117, 228 (2020).<br/>3. A. Y. Kitaev, Physics-Uspekhi, 44, 131 (2001).<br/>4. R. C. Bento Ribeiro et al., Phys. Rev. B 105, 205115 (2022).<br/>5. R. C. Bento Ribeiro et al., submitted