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 suprapar amagnetic 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 thickn ess (3 Angstrom) the Co particle sizes change with the growth rate. This ch ange is observed in the zero-field-cooled and field-cooled magnetisation me asurement and is due to the change of number of nucleation sites with growt h rate. This result is in good agreement with the nucleation theory for epi taxial thin films. High-resolution TEM (HREM) measurement was performed on these samples and it was found that Co grows as 2 monolayer thick islands a nd exhibits relative uniform distribution of particle sizes. (C) 1999 Publi shed by Elsevier Science B.V. All rights reserved.