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 observed 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 theta) (Omega(-1)), where a is the angle between the magnetizations of two iron electrodes. The dependence of the magnetoresistance ratio, saturated resistance and also the tunneling current on temperature were measured in the range 4.2-300 K. The results support the claim that the giant magnetoresistance is due to the magnetic tunneling of electrons between the electrodes through the thin Al2O3 insulator.