Spin Dependent Tunneling Device Utilizing the Magneto-Coulomb Effect

We investigate the magneto-Coulomb effect in a single-electron tunneling transistor (SETT) with ferromagnetic leads. This effect enables us to achieve a magnetic field control, as opposed to the conventional electrical gate control of the SETT. By utilizing the sharp magnetic switching of the ferromagnetic (FM) source and drain electrodes, the magneto-Coulomb effect can attain a large magnetoconductance (MC) change in response to the applied magnetic B-field. We analyze the effect of the B-field on the effective charge Qtilde on the island, and analytically obtain the step change DeltaQtilde at the coercive field B_c of the FM leads. We also derive the optimal biasing conditions of V_g=(nplusmn1/4)e/C_g and V_dsapV_th (threshold bias). Such bias conditions ensure the maximum sensitivity (dI/dQtilde) of the SETT modulation to Qtilde, and hence to the applied B-field. The magnetoconductance response of the SETT under the optimal biasing condition is numerically calculated based on the assumption of single-domain switching of the FM leads