Figure 1:
An open spin chain engineered on the surface. Spins (arrows) are accommodated at iron sites (spheres). A thermal average of the vector spin chirality κ_{i,i+1} formed by two neighboring spins S_{i} and S_{i+1} at site i and i+1 always points to the y direction because of the antisymmetric Dzyaloshinskii-Moriya interaction implemented by the artificial structure. The magnetic field h_{z} acting on an edge pins the otherwise fluctuating spin spiral over a whole finite-size spin chain.