Ferromagnetic resonance study of composite Co/Ni - FeCoB free layers with perpendicular anisotropy

Abstract

We study the properties of composite free layers with perpendicular anisotropy. The free layers are made of a soft FeCoB layer ferromagnetically coupled by a variable spacer (Ta, W, Mo) to a very anisotropic [Co/Ni] multilayer embodied in a magnetic tunnel junction meant for spin torque memory applications. For this we use broadband ferromagnetic resonance to follow the field dependence of the acoustical and optical excitation of the composite free layer in both in-plane and out-of-plane applied fields. The modeling provides the interlayer exchange coupling, the anisotropies and the damping factors. The popular Ta spacer are outperformed by W and even more by Mo, which combines the strongest interlayer exchange coupling without sacrificing anisotropies, damping factors and transport properties.

arXiv commentTo appear the Applied Physics Letters, 2016

References in corpus (4)

• Probing the Dzyaloshinskii-Moriya interaction in CoFeB ultrathin films using domain wall creep and Brillouin light spectroscopy
• Spin-torque driven ferromagnetic resonance of Co/Ni synthetic layers in spin valves
• Ferromagnetic resonance of exchange-coupled perpendicularly magnetized bilayers
• Evolution of perpendicular magnetized tunnel junctions upon annealing

Cited by in corpus (2)

• Annealing stability of magnetic tunnel junctions based on dual MgO free layers and [Co/Ni] based thin synthetic antiferromagnet fixed system
• Spin-torque nano-oscillator based on two in-plane magnetized synthetic ferrimagnets