Figure 1. Atomic and magnetic structures of trimers on Cu(111).

(a) Atomic structure. The magnetic atoms are represented by golden spheres, and part of the Cu(111) substrate is represented by the blue spheres, indicating Cu atoms. The orientations of the spin moments are given by red arrows, and fixed as n_i=(cos ϕ_i sin θ, sin ϕ_i sin θ, cos θ) for i=1, 2, 3. The surface normal defines the z axis and the polar angle θ. (b–d) Magnetic structures, top view (θ=45°). The choice of azimuthal angles ϕ_i defines the (b) ferromagnetic (F: ϕ₁=ϕ₂=ϕ₃=0°), (c) chiral right-handed (R: ϕ₁=0°, ϕ₂=+120°, ϕ₃=−120°) and (d) chiral left-handed (L: ϕ₁=0°, ϕ₂=−120°, ϕ₃=+120°). Atom #1 (encircled) is chosen to have the same orientation of the spin moment in all structures.