Abstract
We present first-principles calculations of a $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R30\ifmmode^\circ\else\textdegree\fi{}$ $\mathrm{Bi}∕\mathrm{Ag}(111)$-ordered surface alloy, which has recently been investigated experimentally using angle-resolved photoemission spectroscopy. The surface states in the $L$-projected bulk band gap show a Rashba-type spin-orbit splitting which is three times larger than what has been observed on a clean Bi(111) surface. This large enhancement can be explained by the strong distortion of the surface-state wave function which is caused by the substantial outward buckling of the Bi atom. Also, in a similar surface alloy, $\mathrm{Pb}∕\mathrm{Ag}(111)$, a strong Rashba-type splitting was found by our calculations. The comparison to the experimental data is more difficult due to the presence of a second, close-by surface state. We discuss the dependence of the two-dimensional band structure on the surface corrugation and compare to the experimental findings.
Highlights
Surface states, which can be regarded to form a twodimensional electron gas in the surfacex, yplane, are frequently described in terms of the kinetic energy of electron with an effective mass m*
We present first-principles calculations of aͱ3 ϫ ͱ3͒R30° Bi/ Ag111͒-ordered surface alloy, which has recently been investigated experimentally using angle-resolved photoemission spectroscopy
Recent experiments have shown that a commensurateͱ3 ϫ ͱ3͒R30° Bi/ Ag surface alloy can be grown on a
Summary
Surface states, which can be regarded to form a twodimensional electron gas in the surfacex , yplane, are frequently described in terms of the kinetic energy of electron with an effective mass m*. Due to the relativistic effects, an electric field Ee.g., the potential gradient normal to the surfaceis seen by the moving electrons as a magnetic field that couples to the spin of the electron. This effect, known as the Rashba effect or Rashba spin-orbit coupling, is described by the Bychkov-Rashba Hamiltonian,. The spin degeneracy of the two-dimensional electron gas provided by the surface states is lifted and the energy dispersion has the form ERSO = ប2 2m* ͑kʈ ± ⌬k2 − ESO
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