Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 72: [MA] Joint Session "Surface Magnetism III" (jointly with O)

O 72.11: Talk

Thursday, March 29, 2012, 18:00–18:15, BH 243

Effect of the external electric field on surface states — •Pavel Ignatiev, Oleg Brovko, and Valeri Stepanyuk — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

We present an ab initio study of surface states exposed to the external electric field (EEF). We consider two examples: the Shockley-type surface state on Cu(111) and spin-polarized surface states arising on Co nanoislands. Using the KKR method supplemented with a possibility to account for the EEF, we demonstrate that the EEF affects both energetics and intensities of surface states. Our results on Cu(111) are compared with recent STS studies on the Stark shift of the Cu(111) Shockley surface state.[1] For spin-polarized surface states on a Co bilayer on Cu(111), we show that the spin-selective screening of the EEF by evanescent vacuum surface states tails leads to a possibility of reversing the sign of the surface states spin polarization.[2] Field-induced variations of the majority and the minority surface states band structures change significantly standing-wave patterns [3] of the spin-polarized electrons opening, thus, another way to locally switch spin-polarization of confined surface states. The effect of the electric field on magnetism of the Co bilayer is characterized also in terms of the effective magnetoelectric coefficient.[4]

[1] L. Limot et al., Phys. Rev. Lett. 91, 196801 (2003); J. Kröger et al., Phys. Rev. B 70, 033401 (2004).

[2] P. A. Ignatiev, V. S. Stepanyuk, Phys. Rev. B 84, 075421 (2011).

[3] H. Oka et al, Science 327, 843 (2010).

[4] C.-G. Duan et al., Phys. Rev. Lett. 101, 137201 (2008).