Evolution of the structure and magneto-optical properties of ion beam synthesized iron nanoclusters

Abstract Changes in the structural, magnetic, and optical

properties are observed during the synthesis of metallic

nanoclusters fabricated on the surface of a thin silica layer

by ion beam implantation of iron atoms. Iron atoms were

implanted to the fluence of 1016 cm-2. The ion implantation

depth in 400-nm thick SiO2 film on a Si (100) substrate

was 25 nm. The implanted samples were subsequently

annealed for periods of seconds to hours at 1000 C with

Electron Beam Annealing. Ellipsometry and Rutherford

Backscattering Spectrometry spectra were fitted with

appropriate models to retrieve the optical characteristics,

composition, and structure of the samples. Magneto Optical

Kerr Effect measurements and SQUID magnetometry

were performed to investigate the effect of the structural

changes identified by TEM measurements on the superparamagnetic

and magneto-optical properties of the

samples during the annealing process. The changes in the

Fe crystalline(core)/amorphous oxide(shell) structure and

the position of the nanoclusters relative to the surface

observed for small annealing durations are shown to

enhance the Kerr effect resulting into high coercive field

and high amplitude in the Kerr rotation and ellipticity.