  In this paper, we attempt the theoretical modeling of the magnetic tunnel
junctions with embedded magnetic and nonmagnetic nanoparticles (NPs). A few
abnormal tunnel magnetoresistance (TMR) effects, observed in related
experiments, can be easily simulated within our model: we found, that the
suppressed TMR magnitudes and the TMR sign-reversing effect at small voltages
are related to the electron momentum states of the NP located inside the
insulating layer. All these TMR behaviors can be explained within the tunneling
model, where NP is simulated as a quantum well (QW). The coherent (direct)
double barrier tunneling is dominating over the single barrier one. The origin
of the TMR suppression is the quantized angle transparency for spin polarized
electrons being in one of the lowest QW states. The phenomenon was classified
as the quantized conductance regime due to restricted geometry.
