Abstract
Ferromagnet/insulator/ferromagnet junctions with Langmuir-Blodgett (LB) films were fabricated. The LB films used were poly-N-dodecylacrylamide (PDDA) and merocyanine (MC) dye. A magnetoresistance ratio of 0.3% at 300 K was observed in the junction with PDDA. This value was small in comparison with the theoretical values. One possible reason for this was the presence of an inelastic tunnel with a molecular vibration. To confirm this possibility, inelastic tunnel spectroscopy was performed. A shift of the peak assigned to the C=O stretching vibration was observed, indicating that electrons are trapped at the carbonyl group and can tunnel between the electrode and the carbonyl group. The junction with MC did not show the magnetic tunneling effect. MC relaxed rapidly to spiropyran (SP) form on the water surface, and the homogeneity of the LB film was lost.
