Spin configuration of ferromagnetic/antiferromagnetic nano-composite particles

A systematic study of the spin configuration of ferromagnetic(core)/antiferromagnetic(shell) nano-composite particles was carried out by two approaches: micromagnetic and atomistic simulations. In the case of strong interlayer exchange coupling between ferromagnet and antiferromagnet, the micromagnetic simulation result is consistent with the atomistic simulation result. However, in the case of weak interlayer exchange coupling the micromagnetic simulation predicts a multi-domain structure of the ferromagnet, which is inconsistent with the atomistic simulation. The failure of micromagnetic simulation in describing the spin structure of the nano-composite particles might be interpreted in terms of the under-estimation of the exchange energy for rapid spatial fluctuations of the magnetization by the continuum exchange formalism or might be due to the cooling process procedure. Also, the variation of spin structure as a function of the uniaxial anisotropy of the core is presented and discussed.