Evolution of perpendicular magnetized tunnel junctions upon annealing

Abstract

We study the evolution of perpendicularly magnetized tunnel junctions under 300 to 400 ${}^{\circ }$C annealing. The hysteresis loops do not evolve much during annealing and they are not informative of the underlying structural evolutions. These evolutions are better revealed by the frequencies of the ferromagnetic resonance eigenmodes of the tunnel junction. Their modeling provides the exchange couplings and the layers' anisotropies within the stack which can serve as a diagnosis of the tunnel junction state after each annealing step. The anisotropies of the two CoFeB-based parts and the two Co/Pt-based parts of the tunnel junction decay at different rates during annealing. The ferromagnet exchange coupling through the texture-breaking Ta layer fails above 375${}^{\circ }$C. The Ru spacer meant to promote a synthetic antiferromagnet behavior is also insufficiently robust to annealing. Based on these evolutions we propose optimization routes for the next generation tunnel junctions.

References in corpus (4)

• Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer
• Quantized spin wave modes in magnetic tunnel junction nanopillars
• Time-resolved spin-torque switching in MgO-based perpendicularly magnetized tunnel junctions
• Bimodal switching field distributions in all-perpendicular spin-valve nanopillars

Cited by in corpus (7)

• Material developments and domain wall based nanosecond-scale switching process in perpendicularly magnetized STT-MRAM cells
• Back-hopping in Spin-Transfer-Torque switching of perpendicularly magnetized tunnel junctions
• Offset fields in perpendicularly magnetized tunnel junctions
• Gilbert damping of high anisotropy Co/Pt multilayers
• Ferromagnetic resonance study of composite Co/Ni - FeCoB free layers with perpendicular anisotropy
• Annealing stability of magnetic tunnel junctions based on dual MgO free layers and [Co/Ni] based thin synthetic antiferromagnet fixed system
• Perpendicularly magnetized CoFeB multilayers with tunable interlayer exchange for synthetic ferrimagnets