MAGNETIC-PROPERTIES OF MAGNETITE ARRAYS PRODUCED BY THE METHOD OF ELECTRON-BEAM LITHOGRAPHY

Arrays of magnetite particles in tile submicron range (0.1 - 4.0 mu m) have been produced. A novel method involving the utilisation of Elect ron Beam Lithography techniques often employed in the engineering desi gn of integrated circuits of microchips was used. The fabrication proc ess involved first producing arrays of iron (Fe) particles and then co nverting them to magnetite (Fe3O4) by thermal treatment. The fabricate d magnetite particles have well controlled parameters including inter- particle spacing, an impossible task to achieve using artificially pro duced powders often employed in rockmagnetic studies. Two methods of c onverting Fe to Fe3O4 by annealing were used. One method led to Fe3O4 grains with high coercivities, typical of stressed grains and tile oth er low coercivities in agreement with those for laboratory grown cryst als. The crystal unit cell edge. Curie temperature, and saturation iso thermal remanent magnetisation (SIRM) intensity observed at the Verwey transition are all consistent with stoichiometric magnetite.