Magnetoresistance of ferromagnetic single-electron transistors

We investigate the magnetoresistance of the single-electron transistor made of ferromagnetic leads and island. By lowering the temperature, the Coulom b blockade of the single electron tunneling is enhanced, which in turn infl uences the magnetoresistance of the device. The corresponding magnetoresist ance ratio as a function of the temperature is studied by taking into accou nt both the spin-dependent tunneling processes and the Coulomb blockade eff ect. Finally, we determine the parameter range, in which the ferromagnetic single-electron transistor can be used as a device with the magnetoresistan ce ratio enhanced by the Coulomb blockade effect. (C) 2000 American Institu te of Physics. [S0003-6951(00)04449-1].