The spin-split states subject to Rashba spin-orbit coupling in two-dimensional systems have long been accepted as pointing inplane and perpendicular to the corresponding wave vectors. This is in general true for free-electron model, but exceptions do exist elsewhere. Within the tight-binding model, we unveil the unusual upstanding behavior of those Rashba spins around K̄ and K̄′ points in honeycomb lattices. Our calculation (i) explains the recent experiment of the Tl/Si (111) - (1×1) surface alloy, where abrupt upstanding spin states near K̄ are observed and (ii) predicts an electrically reversible out-of-plane surface spin polarization.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2009 12月 8
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