Improvement of the uniformity and dipole ferromagnetism in Co nanodots assemblies on Pb/Si(111) via step tuned dimensionality variation

We fabricated quasi-one-dimensional Co nanochain assemblies and two-dimensional Co nanodot assemblies on Pb/Si(111) substrates by step decoration. The morphology and magnetic properties of these two kinds of Co nanodot assemblies were investigated by in situ scanning tunneling microscopy and magneto-optical Kerr effect measurements. It was found that the steps cannot only improve the uniformity of the Co nanodots, but also increase the critical temperature T-c. Monte Carlo simulation indicates that the ferromagnetism mainly originates from the dipolar interactions and the critical temperature T-c can be enhanced by introducing an in-plane uniaxial magnetic anisotropy via the step tuned dimensionality variation of the nanodot assemblies.