Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Moire and Graphene Stacking
O 28.1: Vortrag
Dienstag, 17. März 2015, 14:00–14:15, MA 041
Periodic Overlayers and Moiré Patterns: a unified theoretical treatment. — •Klaus Hermann — Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany)
Complex overlayer structures at single crystal surfaces have been observed where long-range order, expressed by additional approximate surface periodicity with very large unit cells, was found. Examples are Pb(111)-C60 near (√403/7×√403/7)R22.8o [1], Ag(111)-3S near (√7×√7)R19.1o [2], or graphene at different hexagonal metal surfaces, such as Ir(111) [3]. This phenomenon can be characterized by spatial interference resulting in 2-dimensionally periodic Moiré patterns. We have generalized a previously proposed mathematical formalism [4] of determining such Moiré patterns based on concepts of higher-order coincidence (HOC) lattices. The extended formalism provides simple mathematical relations allowing to compute 2-dimensional Moiré lattices of any order in their dependence on layer rotation and scaling with respect to a given HOC lattice structure. The formalism will be illustrated by example systems observed in experiment. [1] H.L. Li, K.J. Franke, J.I. Pascual, L.W. Bruch, R.D. Diehl, Phys. Rev. B 80 (2009) 085415. [2] M. Yu, D.P. Woodruff, C.J. Satterley, R.G. Joes, and V.R. Dhanak, J. Phys. Chem. 111 (2007) 3152. [3] E. Loginova, S. Nie, K. Thürmer, N.C. Bartelt, and K.F. McCarthy , Phys. Rev. B 80 (2009) 085430. [4] K. Hermann, J. Phys.: Condensed Matter 24 (2012) 314210.