Abstract
Double-barrier magnetic tunnel junctions (DMTJs) with an Fe(001) / MgO(001) / Fe(001) / MgO(001) / Fe(001) structure were deposited upon MgO(001) substrates by using molecular beam epitaxy. The DMTJs were found to show the TMR ratio of up to 110% and an extremely small bias voltage dependence (V1/2 = 1.4 V under a positive bias application) at room temperature. We also investigated the middle-layer thickness dependence of the conductance curve in the DMTJs. Clear oscillations of the conductance were observed in a parallel magnetization configuration. This oscillation is thought to originate in the modulation of the tunneling conductance by the spin-polarized quantum well states created in the middle Fe layer.
