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 θ)(Ω^-1), where θ 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.