Thursday, June 27, 2013

1306.6139 (René Hammer et al.)

Dynamics of domain-wall Dirac fermions on a topological insulator: a
chiral fermion beam splitter

René Hammer, Walter Pötz
The intersection of two magnetic domain walls on the surface of topological insulators provides a one-way beam splitter for domain-wall Dirac fermions. Based on an analytic expression for a static two-soliton magnetic texture we perform a systematic numerical study of the propagation of Dirac wave packets along such intersections. A single-cone staggered-grid finite difference lattice scheme is employed in the numerical analysis. It is shown that the angle of intersection plays a decisive role in determining the splitting ratio of the fermion beam. For a non-rectangular intersection, the width and, to a lesser extent, the type of domain walls, e.g. Bloch or N{\'e}el, determine the properties of the splitter. An electric gate placed near the intersection offers a dynamic external control knob for the splitting ratio. Beam splitters of this kind provide the building blocks for more complex one-way chiral fermion circuits.
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