Single-electron spin interplay for characterization of magnetic double tunnel junctions.

Building on spin-modified Coulomb blockade theory, we derive an approximate analytical solution which matches closely to the existing numerical models in the limit of a large difference in the resistance of the two tunnel junctions. Using this, we are able to explore the properties of an I(V) measurement for a double tunnel junction incorporating a nanoparticle in various magnetic configurations. It is shown that this information allows, under certain conditions, seven of the device's physical parameters to be determined in a single I(V) sweep, including individual junction capacitances and spin-dependent resistances. The tunnel magnetoresistance and spin polarizations are also examined in the light of this solution and are shown to be similar in nature and dominated by the magnetic properties of the most resistive barrier. It is shown that spin injection and detection are theoretically possible in a single device containing a nonmagnetic nanoparticle, suggesting a novel means of measuring the tunnel spin polarization of ferromagnetic materials. [ABSTRACT FROM AUTHOR]