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This study presents the effective tuning of perpendicular magnetic anisotropy in CoFeB/MgO thin films by He+ ion irradiation and its effect on domain wall motion in a low field regime. Magnetic anisotropy and saturation magnetisation are found to decrease as a function of the irradiation dose which can be related to the observed irradiation-induced changes in stoichiometry at the CoFeB/MgO interface. These changes in the magnetic intrinsic properties of the film are reflected in the domain wall dynamics at low magnetic fields (H) where irradiation is found to induce a significant decrease in domain wall velocity (v). For all irradiation doses, domain wall velocities at low fields are well described by a creep law, where Ln(v) vs. H−1∕4 behaves linearly, up to a maximum field H*, which has been considered as an approximation to the value of the depinning field Hdep. In turn, H* ≈ Hdep is seen to increase as a …
AIP Publishing LLC
Publication date: 
20 Jul 2015

L Herrera Diez, F García-Sánchez, J-P Adam, T Devolder, S Eimer, MS El Hadri, A Lamperti, R Mantovan, B Ocker, D Ravelosona

Biblio References: 
Volume: 107 Issue: 3 Pages: 032401
Applied Physics Letters