Magnetoresistance modulation in single-electron transistors

The tunneling magnetoresistance (TMR) of a ferromagnetic single-electron transistor, consisting of an ultrasmall "island" electrode separated from contact electrodes by thin tunnel barriers, is modeled. The TMR of the device can be modulated externally via gate V/sub g/ or source-drain V voltages. When the tunnel resistance R/sub t/ is highly asymmetric, the TMR shows periodic spike modulation with V/sub g/. For symmetric R/sub t/, a linear (sawtooth) modulation occurs instead. In the presence of spin accumulation, a sharp change of TMR ratio of up to 25% is obtained at a certain critical voltage.