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[Co0.4 nm/Pd0.7 nm]50 multilayers with Pd film thicknesses in the first ferromagnetic maximum of interlayer exchange coupling display almost purely perpendicular-to-plane anisotropy and labyrinth stripe domain patterns in remanence. Their magnetization reversal is characterized by domain nucleation starting at a defined field HN and domain wall movement in a defined magnetic field range. The modification of the magnetization reversal by 10 keV He ion bombardment due to the reduced magnetic anisotropy has been investigated by polar magneto-optical Kerr effect, by vibrating sample magnetometry, and by magnetic force microscopy at room temperature. It is shown that the ion bombardment creates and increases areas with ferromagnetic in-plane anisotropy and proportions of the sample showing superparamagnetism, the latter predominantly in the deeper layers. [ABSTRACT FROM AUTHOR]

Sputter deposited Mn83Ir17(30 nm)/Co70Fe30(10 nm)/Ta thin films have been investigated for their thermal exchange bias field drift at different storage temperatures after 10 keV He+ ion bombardment in an externally applied in-plane magnetic field. It is experimentally shown that the drift coefficient in an intermediate time interval, as given in a recently developed model, is proportional to T and proportional to the initial number of coupling sites in the polycrystalline exchange bias layer system used. [ABSTRACT FROM AUTHOR]

The thermal exchange bias field drift of sputter deposited Mn83Ir17(15 nm)/Co70Fe30(10 nm)/Ta thin films at room temperature after 10 keV He+ ion bombardment in an externally applied in-plane magnetic field for different ion fluences was studied. Although field cooling of the layer system resulted in a temporally stable exchange bias field at room temperature the exchange bias field starts to drift after ion bombardment like in non-annealed samples. Between 1 and 648 h after ion bombardment a logarithmic increase in the absolute magnitude of the exchange bias field is observed. A tentative model is presented for its description based on noninteracting domains in the antiferromagnet. A comparison between experimental data and the model reveals the delicate interplay between the ion bombardment modified average antiferromagnetic anisotropy constants, exchange coupling constants, and relaxation time distributions in the polycrystalline layer system influencing the thermal drift velocities. [ABSTRACT FROM AUTHOR]

A quantitative analysis of magnetic force microscopy (MFM) images taken in external in-plane magnetic fields is difficult because of the influence of the magnetic field on the magnetization state of the magnetic probe tip. We prepared calibration samples by ion bombardment induced magnetic patterning with a topographically flat magnetic pattern magnetically stable in a certain external magnetic field range for a quantitative characterization of the MFM probe tip magnetization in point-dipole approximation. [ABSTRACT FROM AUTHOR]

A new plasma ion source for in situ keV He ion bombardment of solid state samples or thin films was designed and built for ion fluences between 1 × 1012 and 1 × 1017 ions/cm2. The system was designed to be mounted to different diffraction chambers for soft x-ray resonant magnetic scattering. Without breaking the vacuum due to He-ion bombardment, structural and magnetic modifications of the samples can be studied in situ and element specifically. [ABSTRACT FROM AUTHOR]

Currently, much attention is being paid to patterned multilayer systems in which there exists a perpendicular magnetic anisotropy, because of their potential applications in spintronics devices and in a new generation of magnetic storage media. To further improve their performance, different patterning techniques can be used, which render them suitable also for other applications. Here we show that He+ 10 keV and Ar+ 100 keV ion bombardment of (Ni80Fe20-2 nm/Au-2 nm/Co-0.6 nm/Au-2 nm)10 multilayers through colloidal mask enables magnetic patterning of regularly arranged cylindrical magnetic domains, with perpendicular anisotropy, embedded in a non-ferromagnetic matrix or in a ferromagnetic matrix with magnetization oriented along the normal. These domains form an almost perfect two-dimensional hexagonal lattice with a submicron period and a large correlation length in a continuous and flat multilayer system. The magnetic anisotropy of these artificial domains remains unaffected by the magnetic patterning process, however the magnetization configuration of such a system depends on the magnetic properties of the matrix. The micromagnetic simulations were used to explain some of the features of the investigated patterned structures. [ABSTRACT FROM AUTHOR]