Switching stability of magnetic tunnel junctions with an artificial antiferromagnet

Avoiding fatigue in the switching of magnetic tunnel junctions is crucial for their long-term use in nonvolatile magnetic memories. We compare the switching stability of two types of junctions with different soft layers: Fe or ${\mathrm{Ni}}_{\mathrm{81}}{\mathrm{Fe}}_{\mathrm{19}},$ both with Co dusting at the barrier interface. The magnetically hard electrode is a Co/Cu/Co artificial antiferromagnet. While the tunneling magnetoresistance (TMR) remains unchanged after ${10}^4$ cycles in a 4 kA/m rotating field, it decreases by more than 45% due to uniaxial switching. Fringing fields of domain walls in the soft layer and an intrinsic instability of Co/Cu/Co are identified as the main reasons. Magnetization reversal by two perpendicular switching pulses avoids this magnetic degradation and maintains a full TMR signal.