Rare-earth-containing planar magnetic materials formed using Langmuir–Blodgett technique

We describe the preparation and characterization of rare-earth-containing stearic acid Langmuir–Blodgett (LB) films. Stearic acid monolayer behavior on the rare-earth-containing aqueous subphase has been analyzed by thermodynamic measurements. The monolayer compression isotherm shape changed substantially by varying the anion type at the constant rare-earth cation content and pH in aqueous subphase. The conditions necessary to form highly integrated mono- and multilayered rare-earth-containing LB films were investigated. The deposited mono- and multilayer gadolinium (Gd)-containing LB films were studied by scanning tunneling microscopy (STM) and electron paramagnetic resonance (EPR) techniques. The temperature dependence of EPR signal in Gd-containing LB films indicates the magnetic ordering with a characteristic temperature of transition to complete disordered paramagnetic state of about 500 K, significantly higher than Curie temperature in bulk metal Gd. Low-field hysteresis of microwave absorption was observed in these films and pointed out to the existence of remanence magnetism in created material.