Progressive\nControl of Rashba State on Topological\nDirac Semimetal KZnBi

Rashba\nstates have been actively revisited as a platform for advanced\napplications such as spintronics and topological quantum computation.\nYet, access to the Rashba state is restricted to the specific material\nsets, and the methodology to control the Rashba state is not established.\nHere, we report the Rashba states on the (001) surface of KZnBi, a\n3D Dirac semimetal. Using angle-resolved photoemission spectroscopy\nand first-principles calculations, we investigated the evolution of\nRashba states under different surface conditions controlled by alkali\nmetal deposition. We observed that restoring surface ordering enables\na Rashba state, which is absent in freshly cleaved surfaces. Interestingly,\nwe were able to modify the dispersion of the Rashba state from an\nordinary parabolic dispersion to a linearly dispersing Dirac-like\nstate by additional alkali-metal deposition. Our findings provide\na methodology for engineering the properties of Rashba states for\nadvanced applications and redefine topological systems as generic\nhosts of Rashba states.