Tunnel magnetoresistance on ferromagnetic single-electron transistors withmultiple tunnel junction

Single-electron transistors with ferromagnetic multiple tunnel junctions ar e studied theoretically. Tunnel magnetoresistance under the Coulomb blockad e regime is modulated by the gate voltage and is increased with increasing the number of tunnel junctions. Higher-order tunneling processes, especiall y for inelastic macroscopic quantum tunneling of charge, play an important role in the enhancement of the tunnel magnetoresistance. This implies that the tunnel magnetoresistance of the ferromagnetic single-electron transisto r could be controlled by the gate and drain voltages and the number of the tunnel junctions. (C) 2001 American Institute of Physics.