Influence of topography and Co domain walls on the magnetization reversal of the FeNi layer in FeNi/Al$_2$O$_3$/Co magnetic tunnel junctions

Fabien Romanens (1) , Jan Vogel (1) , Wolfgang Kuch (2) , Keiki Fukumoto (2) , Julio Camarero (3) , Stefania Pizzini (1) , Marlio Bonfim (1, 4) , Frédéric Petroff (5)

1 LLN - Laboratoire Louis Néel
2 FU BERLIN - Institut für Experimentalphysik
3 FMC - Departamento de Fisica de la Materia Condensada [Madrid]
4 Departamento de Engenharia Elétrica
5 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)

We have studied the magnetization reversal dynamics of FeNi/Al$_2$O$_3$/Co magnetic tunnel junctions deposited on step-bunched Si substrates using magneto-optical Kerr effect and time-resolved x-ray photoelectron emission microscopy combined with x-ray magnetic circular dichroism (XMCD-PEEM). Different reversal mechanisms have been found depending on the substrate miscut angle. Larger terraces (smaller miscut angles) lead to a higher nucleation density and stronger domain wall pinning. The width of domain walls with respect to the size of the terraces seems to play an important role in the reversal. We used the element selectivity of XMCD-PEEM to reveal the strong influence of the stray field of domain walls in the hard magnetic layer on the magnetic switching of the soft magnetic layer.

Mots clés: XMCD; nucleation; magnetic tunnel junction; PEEM; magnetization dynamics; domain walls

Domaines: Autre [cond-mat.other]

Fabien Romanens, Jan Vogel, Wolfgang Kuch, Keiki Fukumoto, Julio Camarero, et al.. Influence of topography and Co domain walls on the magnetization reversal of the FeNi layer in FeNi/Al$_2$O$_3$/Co magnetic tunnel junctions. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2006, 74, pp.184419. ⟨10.1103/PhysRevB.74.184419⟩. ⟨hal-00104365⟩