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Perpendicular magnetic anisotropy (PMA) in transition metal thin films offers a pathway for enabling the interesting physics of nanomagnetism and developing a wide range of spintronics applications. We demonstrate a simple method to obtain Ni thin films with PMA by depositing them onto nanoporous anodic alumina membranes (NPAAMs), with different pore diameters varying in the range between 32 ± 2 and 93 ± 1 nm. Thus, several sets of Ni antidot arrays thin films have been fabricated with different hole diameters, 35 nm ≤ d ≤ 89 nm, and fixed interhole distances, D int , around 103 ± 2 nm but reducing the edge-to-edge separation between adjacent antidots, (W = D int − d), and in two different situations, by considering that W is well above or below the layer thickness, t, of the thin film. The crossover from the in-plane magnetization to out of plane magnetization in a ferromagnetic thin film has been achieved by modifying only the nanopore size of the patterned anodic alumina template and the experimental results were supported by micromagnetic simulations performed with Mumax 3 code. A dramatic change in the coercivity, H C , dependence with d and W parameters has been observed with a critical nanohole diameter, d c , at which the appearance of the perpendicular magnetization is observed. The decreasing of the inplane coercivity for samples with d > 75 nm is due to the weakened of the in-plane magnetic anisotropy and the rising of the out of plane component. The effective perpendicular magnetic anisotropy energy density for Ni antidot thin film with d = 90 nm and t = 20 nm is around 1.44 erg/cm 2 , larger than that obtained by traditional approaches for Ni films with PMA (0.03−0.2 erg/cm 2 ). These findings point toward antidot thin films as novel routes to engineer the magnetic behavior of ferromagnetic metal with large PMA, which might entail a milestone for future applications in bit patterned magneto-optic perpendicular recording media and spintronic devices.

The growth of nanostructured materials by means of different deposition methods employing nanoporous anodic aluminum oxide membranes as patterned templates has been widely used during last years due to the outstanding features displayed by these nanoporous templates. Here we report on the synthesis, morphology and magnetic properties exhibited by novel magnetic 1D and 2D nanostructured materials having nanowire or antidot thin films geometry, respectively, together to that of geometrically diameter modulated ferromagnetic nanowires. Their magnetic properties will be analyzed and discussed based on the different anisotropic behavior derived from their morphological and microstructural features.

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Influence of nanoholes array geometrical parameters 2 | 30 of high interest for the development of novel magnetic sensors and for thermo-magnetic recording patterned media based on template-assisted deposition techniques.