Physics of Stepped Surfaces: Spinless Fermions and Beyond

DIPC Seminars

Theodore L. Einstein (Dep. of Physics, U. of Maryland, USA)
Donostia International Physics Center
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Physics of Stepped Surfaces: Spinless Fermions and Beyond ** ** **Physics of Stepped Surfaces: Spinless Fermions and Beyond** __ _Theodore L. Einstein_ _ _ _Dep't of Physics, U. of Maryland, College Park, MD 20742-4111 USA_ _einstein@umd.edu_ Stepped surfaces provide an ideal physics problem: a host of practical applications in a system with rich theoretical underpinnings. The basics have been known for some time, and are based on the analogy between step configurations in two dimensions and the world lines of evolving spinless fermions in one spatial dimension. The distribution of separations can be well described with ideas from universal properties of fluctuations. There are some noteworthy shortcomings of the analogy: Unlike fermions, steps can touch (thereby forming double-height steps), just not cross. For typical orientations, there is an offset (affine) term when determining the spacing between steps, which leads to some curious effects when ignored. For vicinal surfaces with metallic surface states on the terraces, there is a second length (the Fermi wave length) in addition to the mean step separation, destroying the scaling of the TWD plotted vs. normalized spacing. Local experiments by Ortega and co-workers on curved crystals offer the exciting prospect of confronting these behaviors by investigating multiple vicinal surfaces of the same material with various misorientations (mean spacings between steps).