GIANT MAGNETIC TUNNELING EFFECT IN FE AL2O3/FE JUNCTION/

A giant magnetoresistance ratio of 30% at 4.2 K and 18% at 300 K was o bserved for the first time in an Fe/Al2O3/Fe junction. The conductance at room temperature was expressed well by G = 96.2 (1 + 0.09 cos thet a) (Omega(-1)), where a is the angle between the magnetizations of two iron electrodes. The dependence of the magnetoresistance ratio, satur ated resistance and also the tunneling current on temperature were mea sured in the range 4.2-300 K. The results support the claim that the g iant magnetoresistance is due to the magnetic tunneling of electrons b etween the electrodes through the thin Al2O3 insulator.