Ion beam smoothing with low-energy argon ions and reduction of Néel “orange peel” coupling in magnetic tunnel junctions

The influence of low-energy argon bombardment with an ion energy of 30-70 eV and normal incidence on the morphology of a 15-nm-thick Ni81Fe19 film on SiO2 has been studied at room temperature. Scanning tunneling microscope measurements show a reduction of the root-mean-square roughness of over 40%. For magnetic tunnel junctions prepared by involving ion-beam smoothing process, the Néel coupling is substantially reduced and measured by magneto-optic Kerr magnetometry.