Spin-texture and magnetic anisotropy of Co adsorbed Bi$_2$Se$_3$ topological insulator surfaces

TL;DR

This study uses first-principles calculations to analyze how cobalt adatoms influence the magnetic anisotropy and spin-texture of Bi$_2$Se$_3$ topological insulator surfaces, revealing dominant out-of-plane magnetism and preserved helical spin textures.

Contribution

It provides new insights into the magnetic properties and spin textures induced by Co adatoms on Bi$_2$Se$_3$ surfaces using first-principles methods.

Findings

Cobalt adatoms induce stable out-of-plane magnetic moments.

Surface states retain helical spin-texture despite Co adsorption.

Out-of-plane magnetism dominates over planar components.

Abstract

Based upon first-principles methods, we investigate the magnetic anisotropy and the spin-texture of Co adatoms embedded in the topmost Se network of the topological insulator Bi$_2$Se$_3$ surface. We find the formation of energetically stable magnetic moment perpendicular to the surface plane, S$_z$. Our results for the pristine Bi$_2$Se$_3$ surface indicate the presence of helical spin-texture not only in the massless surface Dirac states, but also surface states resonant within the valence band present spin-texture. On the other hand, upon the presence of Co adatoms we find that the out-of-plane surface magnetism represents the dominant spin state (S$_z$), while the planar spin components, S$_x$ and S$_y$, are almost suppressed.