Oxygen-mediated Mn diffusion in magnetic tunnel junctions comprising a nano-oxide layer

Mn diffusion toward the tunnel barrier in the hard layer system of a magnetic tunnel junction is recognized as the limitation for the temperature stability. In a series of experiments, a nano-oxide layer (NOL) was included into the hard layer as a diffusion barrier. The tunnel magnetoresistance (TMR) ratio has been monitored and interpreted as a function of anneal temperature, in combination with Auger analysis. At elevated anneal temperature, a more pronounced TMR decay was observed that originates in a different diffusion mechanism for Mn atoms, compared to tunnel junctions without NOL.