Abstract
Using photoemission electron microscopy, we study the magnetization orientation in single 5–25 nm iron particles coupled to a ferromagnetic cobalt support. We find a noncollinear alignment between the particle and substrate magnetization above a particle size of and a parallel alignment for smaller sizes. Numerical calculations reveal a transition from an exchange-dominated to an anisotropy-dominated regime on increasing the particle height: the smaller particles are in a single-domain collinear state while larger particles exhibit a spin-spiral magnetic structure determined by the magnetic anisotropy energy.
- Received 7 December 2009
DOI:https://doi.org/10.1103/PhysRevLett.104.127201
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