Effects of resonant tunneling on magnetoresistance through a quantum dot

The effect of resonant tunneling on magnetoresistance (MR) is studied theor etically in a double-junction system. We have found that the ratio of the M R of the resonant peal; current is reduced more than that of the single jun ction, whereas that of the valley current is enhanced depending on the chan ge of the discrete energy level under the change of magnetic field. We also found that the peak current-valley current ratio decreases when the juncti on conductance increases under the change of the alignment of the magnetiza tions of the two outer electrodes. [S0163-1829(99)02807-6].