Switching stability of magnetic tunnel junctions with an artificial antiferromagnet

Avoiding fatigue in the switching of magnetic tunnel junctions is crucial f or their long-term use in nonvolatile magnetic memories. We compare the swi tching stability of two types of junctions with different soft layers: Fe o r Ni81Fe19, both with Co dusting at the barrier interface. The magnetically hard electrode is a Co/Cu/Co artificial antiferromagnet. While the tunneli ng 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. F ringing fields of domain walls in the soft layer and an intrinsic instabili ty of Co/Cu/Co are identified as the main reasons. Magnetization reversal b y two perpendicular switching pulses avoids this magnetic degradation and m aintains a full TMR signal. (C) 2000 American Institute of Physics. [S0003- 6951(00)01447-9].