Local transport properties of Al2O3 tunnel barriers have been investigated at a nanometric spatial scale with an unconventional near field microscope. Using the tunneling effect, which is extremely sensitive to fluctuations of the barrier parameters (less than 1 to 2 Å), a unique method is introduced to investigate the tunnel barrier quality. This technique provides atomic scale information on the barrier characteristics which cannot be obtained

A powerful technique for investigating field-dependent micromagnetism in thin magnetic layers is presented. The technique uses the spin-polarized tunnel-transport mechanism in magnetic-tunnel junctions. We used this technique to study the micromagnetic-reversal mechanism in an artificial ferrimagnetic system, which consists of two ferromagnetic layers strongly antiferromagnetically coupled through a nonmagnetic interlayer. We show that the high sensitivity