Magnetic tunnel junctions with compensated magnetic moment by directly exchange-coupled NiFe/CoGd/NiFe trilayers

The compensation of magnetic moments plays a major role in magnetic tunnel junction electrodes and is usually established by artificial trilayer ferrimagnets such as CoFe/Ru/CoFe. An alternative route is described here: trilayers consisting of ferromagnetic rare earth and transition metals show an antiparallel exchange coupling of the individual layers. In magnetic tunnel junctions consisting of IrMn exchange biased NiFe/CoGd/NiFe trilayers the total magnetic moment can thus be compensated by an appropriate choice of the individual layer thicknesses. Consequently, an enhancement of the exchange bias field and a strong reduction of the Neel coupling can be found in parallel. The compensation point can be shifted on the temperature scale by the CoGd composition, even to values above room temperature. (c) 2006 American Institute of Physics.