The Strain-assisted Nucleation and Growth Behavior of Co Islands: An Indirect Study of Nanopatterning Using the Remanent Magnetization Measurement (Δm)

摘要

Nanopatterning through strain-assisted nucleation of metal adatom islands is experimentally studied using a magnetic remanence or Δm measurement. The strain field is generated by a square array of interfacial misfit dislocations with a spacing of 4.1 nm due to the lattice mismatch of the epitaxial Pt(002) film on MgO(002) substrates. The intensity of strain is controlled by changing the thickness of the Pt underlayer ranging from 2.0 to 10.0 nm. The amount of exchange coupling among the Co grains grown on Pt template is measured using the Δm technique as an indirect indicator of magnetic grain distribution. From the measured Δm values, the morphology of adatom islands is indirectly deduced. The Co islands on a 5,0 nm thick Pt underlayer show the overall negative behavior of Δm curve, i.e., the strongest nanopatterning effect. Strain driven nucleation is found to be achievable through a narrow selection of experimental growth conditions.