First-principles study of the nontrivial topological phase in chains of 3d transition metals deposited at superconducting surface

Recent experiments have shown the signatures of Majorana bound states at the ends of magnetic chains deposited on a superconducting substrate [1,2]. Here, we employ first-principles calculations to directly investigate the topological properties of 3d transition metal nanochains (i.e., Mn, Cr, Fe, and Co). In contrast to the previous studies, we found the exact tight-binding models in the Wannier orbital basis for the isolated chains aswell as for the surface-deposited wires. Based on these models, we calculate the topological invariant for all systems. For the isolated chains we demonstrate the existence of the topological phase only in Mn and Co systems. Next, we showed that a coupling between the chain and substrate leads to strong modification of the band structure. Moreover, the analysis of the topological invariant indicates the possibility of emergence of the topological phase in all studied nanochains deposited on the Pb surface. Therefore, our results demonstrate an important role of the coupling between deposited atoms and a substrate for topological properties of nanosystems, that should be implemented in future studies [3].

[1] Nadj-Perge et al., Science 346, 602 (2014).
[2] Ruby et al., Nano Lett. 17, 4473 (2017).
[3] A. Kobialka et al., Phys. Rev. B 101, 205143 (2020).