Large Chiral Orbital Texture and Orbital Edelstein\nEffect in Co/Al Heterostructure

Recent experiments\nby S. Krishnia et al. [<i>Nano Lett</i>. <b>2023</b>, <i>23</i>, 6785] reported an unprecedentedly\nlarge enhancement of torques upon inserting thin Al layer in Co/Pt\nheterostructure that suggested the presence of a Rashba-like interaction\nat the metallic Co/Al interface. Based on first-principles calculations,\nwe reveal the emergence of a large helical orbital texture in reciprocal\nspace at the interfacial Co layer, whose origin is attributed to the\norbital Rashba effect due to the formation of the surface states at\nthe Co/Al interface and where spin–orbit coupling is found\nto produce smaller contributions with a higher-order winding of the\norbital moments. Our results unveil that the orbital texture gives\nrise to a nonequilibrium orbital accumulation producing large current-induced\ntorques, thus providing an essential theoretical background for the\nexperimental data and advancing the use of orbital transport phenomena\nin all-metallic magnetic systems with light elements.