Ultrathin Fe-oxide layers made from Langmuir-Blodgett films

Thin Fe-oxide films (15-150 nm thick) have been prepared using Langmuir-Blo dgett (LB) films as precursors consisting of a certain number of Fe-arachid ate monolayers (ML). The organic component of the LB films was removed by d ifferent heating procedures: heating in ambient air at 360 and 900 degrees C, and at 500 degrees C in a H-2 gas flow. The remaining Fe-oxide films wer e analyzed by a number of methods. The most important results are: all Fe-o xide films are smooth and homogeneous (roughnesses between 0.8 and 4 nm), t he magnetic properties are, however, not sufficient for an application as m agnetic storage medium. Only a him prepared from 35 ML Fe-arachidate by hea ting at 500 degrees C in H-2 had magnetic properties (hysteresis loop of th e single domain type, large coercivity and saturation magnetization) suited to use the film as a high data density magnetic storage medium. The films heated at ambient air consist mainly of alpha-Fe2O3. In addition they conta in most probably gamma-Fe2O3 and Fe3O4 (films heated at 360 degrees C) or F e3O4 and FeO (films heated at 900 degrees C). Films healed in H-2 consist o f Fe3O4, FeO and metallic alpha-Fe. (C) 1999 Elsevier Science S.A. All righ ts reserved.