Dependence of Co particle size on the growth rate in the MBE grown Co/Au superparamagnetic multilayers

In this paper, we show that Co\Au multilayers grown by MBE exhibit supraparamagnetic properties when the Co thickness is below 4 Angstrom. By varying the growth rate of Co layers, it was found that for the same nominal thickness (3 Angstrom) the Co particle sizes change with the growth rate. This change is observed in the zero-field-cooled and field-cooled magnetisation measurement and is due to the change of number of nucleation sites with growth rate. This result is in good agreement with the nucleation theory for epitaxial thin films. High-resolution TEM (HREM) measurement was performed on these samples and it was found that Co grows as 2 monolayer thick islands and exhibits relative uniform distribution of particle sizes. (C) 1999 Published by Elsevier Science B.V. All rights reserved.