Ultrathin films: Light and ions irradiations induced changes of magnetic properties

When decreasing ultrathin film thickness d, an increase of the perpendicular magnetic anisotropy (PMA) occurs, resulting in the magnetization reorientation phase transition (RPT) from the in-plane to out-of-plane magnetization state below the critical thickness dRPT. The results of combined experimental, analytical, and micromagnetic simulations studies on the evolution of magnetization states and processes in ultrathin films and multilayered systems [1] will be presented. Possibilities of tuning the magnetic domain sizes in a broad range (of several orders of magnitude) by changing the geometrical parameters of the nanostructure, as well as by an applied external magnetic field will be discussed. Transitions between two- and three-dimensional magnetization distributions will be shown.
As a result of the ion irradiation of the metallic ultrathin films, a decrease of PMA was usually reported [2]. Contrariwise, Ga+ ion irradiation driven creation of the out-of-plane magnetization states, dependent on ion fluence, have been found [3]. Similarly, femtosecond light pulses of high energy density may also induce irreversible enhancement of PMA [4], while low energy density pulses can be used to trigger the magnetization oscillations, via reversible thermal changes of the magnetic anisotropy [5].
1. A. Maziewski, J. Fassbender, J. Kisielewski, M. Kisielewski, Z. Kurant, P. Mazalski, F. Stobiecki, A. Stupakiewicz, I.Sveklo, M.Tekielak, A.Wawro, and V. Zablotskii, Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers, Phys. Status Solidi A, 211, 1005 (2014).
2. H. Bernas (Ed.), Materials Science with Ion Beams, Vol. 116 (Springer-Verlag, Berlin, Berlin, 2010).
3. A. Maziewski, P. Mazalski, Z. Kurant, M. O. Liedke, J. McCord, J. Fassbender, J. Ferré, A. Mougin, A. Wawro, L. T. Baczewski, A. Rogalev, F. Wilhelm, and T. Gemming, Tailoring of magnetism in Pt/Co/Pt ultrathin films by ion irradiation, Phys. Rev. B 85, 054427 (2012).
4. J. Kisielewski, W. Dobrogowski, Z. Kurant, A. Stupakiewicz, M. Tekielak, A. Kirilyuk, A. Kimel, Th. Rasing, L. T.Baczewski, A. Wawro, K. Balin, J. Szade, and A. Maziewski, Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses, Journal of Applied Physics 115, 053906 (2014),
5. J. Kisielewski, A. Kirilyuk, A. Stupakiewicz, A. Maziewski, A. Kimel, Th. Rasing, L. T. Baczewski, and A. Wawro, Laser-induced manipulation of magnetic anisotropy and magnetization precession in an ultrathin cobalt wedge, Phys. Rev. B 85 (2012) 184429.