Spin structure of the Shockley surface state onAu(111)

Abstract

The free-electron like surface state on the (111) surface of gold shows a splitting into two parabolic subbands induced by the spin orbit interaction. Spin-resolved high-resolution photoemission experiments performed with a full three-dimensional spin polarimeter provide a detailed image of the resulting spin structure. In particular, spin-resolved momentum distribution maps show that the spin vector lies in the surface plane and is perpendicular to the momentum of the electrons as expected in a free-electron model. This method of measuring the spin structure of a two-dimensional electron gas allows the observation of the direction of electric fields as probed by the electrons. Although the energy splitting can only be understood as a consequence of strong atomic electric fields, no modulation of the spin direction due to these fields is detected.

Can spin-polarized photoemission measure spin properties in condensed matter?

“…An ARPES study of a surface state on Au(111) by LaShell et al [8] initiated this topic when they found an energy splitting proportional to the electron momentum, which they correctly interpreted as being due to the Rashba effect [9], which was hitherto known only in semiconductor physics. Experimental confirmation of the spin polarized and non-degenerate character came a few years later by Hoesch et al [10] from spin-polarized ARPES (SARPES) data, which showed also the helical nature of the spin structure in these bands. The method has seen a veritable boost after the discovery of topological insulators [11,12] where SARPES data provided direct evidence for the existence of spinpolarized surface states, including their unconventional spin textures [13,14].…”

Observation of a large-gap topological-insulator class with a single Dirac cone on the surface

“…1f). This is generally true for all known spin-orbit-coupled material surfaces such as gold [25,26] class in the Fu-Kane-Mele classification scheme [7].…”

“…bands that are shifted in momentum space from each other, with both enclosing theΓ-point [25,26]. The resulting FS topology leads to a 2π or 0 Berry phase because the phases from the two rings add or cancel.…”

Variation of the character of spin-orbit interaction by Pt intercalation underneath graphene on Ir(111)

“…The most important breakthroughs in this field are Rashba systems [1][2][3][4] and topological insulators [5][6][7]. Both are characterized by two-dimensional electronic states, which are spin polarized owing to the high magnitude of spin-orbit interaction (SOI).…”