Polarized Majorana fermions in double Kitaev zigzag honeycomb nanoribbons

In this work, we study Majorana fermions' formation at the ends of a finite double spin-Kitaev zigzag honeycomb nanoribbon (KZHNR). We characterize the system using a tight-binding minimal model that consists of the first nearest neighbor hopping, the intrinsic Rashba spin-orbit coupling, the triplet superconducting pairing between the atomic spins of the double ZHNR edges, and an external exchange magnetic field.

The band structure and the density of states, for the infinite case, exhibit several topological phase transitions associated with the polarized (spin-up or spin-down) Majorana fermions. The results show that the system develops spin-polarized Majorana with half-metallic behavior. We also calculate the energy spectrum as a function of the chemical potential for the finite double spin-KZHNR. The energy spectrum exhibits chemical potential spin-polarized regions with only spin-up or spin-down Majorana zero-energy modes. Those polarized zero-energy modes are closely related to the topological phase transitions exhibited by the corresponding infinite ZHNR. We also propose a possible experimental realization of the double spin-KZHNR.