MgO-TbFeCo interface enhancement of TbFeCo-based perpendicular magnetic tunnel junctions

Abstract We study the effect of inserting Fe and FeCo thin layers between the MgO and the magnetic layer in the TbFeCo-based perpendicular magnetic tunnel junction (pMTJ). Different half and full structure MTJ were prepared and thin layers of Fe and FeCo were inserted between the MgO-TbFeCo interface. It is observed that in both the reference and free layer half structures, the coercivity decreases on inserting Fe or FeCo thin layer. In magnetic tunnel junction full structure, the minor and major loop coercivities increase with FeCo insertion. The transmission electron microscope images of magnetic tunnel junctions show the MgO interface becomes smoother with FeCo-insertion. The difference in the half and full structure magnetic properties attribute to the FeCo crystal orientation. Both the Fe and FeCo insertion gives large coercivity to the MTJ free and reference layers and made the MgO-TbFeCo interface smoother. The magnetic annealing of MTJs shows an advantage over the zero-field annealing. The magnetic annealing up to 250 °C improves the squareness of the MTJ’s. This study suggests that the Fe/FeCo thin layer insertion to the TbFeCo-based MTJ will be useful in the fabrication of high performance magnetic random-access memories.