Spin-dependent tunneling through NiFe nanoparticles.

Double magnetic tunnel junctions (DMTJs) have been fabricated using alumina barriers with NiFe particles (∼1.8 nm) embedded within. The junctions exhibit spin-dependent transport properties and Coulomb blockade effects. We study differences between control samples and the DMTJs; specifically I-V characteristics and tunnel magnetoresistance (TMR) versus bias voltage characteristics. Clear differences in the systems are evident: the DMTJ with NiFe particles shows a marked peak in TMR at low bias, whereas the dependence of TMR on bias is much weaker for the control MTJ without embedded particles. Hence the TMR at low bias is enhanced by the Coulomb blockade effects. [ABSTRACT FROM AUTHOR]