Nickel Antidot Arrays on Anodic Alumina Substrates
  Large area nickel antidot arrays with density up to 10^10 /cm^2 have been fabricated by depositing nickel onto anodic aluminum oxide membranes that contain lattices of nanopores. Electron microscopy images show a high degree of order of the antidot arrays. Various sizes and shapes of the antidots were observed with increasing thickness of the deposited nickel. New features appear in the antidot arrays in both magnetization and transport measurements when the external magnetic field is parallel to the current direction, including an enhancement and a nonmonotonous field dependence of the magnetoresistance, larger values of the coercive field and remanence moment, and smaller saturation field. 
Z.L. Xiao, Catherine Y. Han, U. Welp, H.H. Wang, V.K. Vlasko-Vlasov,   W.K. Kwok, D.J. Miller, J.M. Hiller, R.E. Cook, G.A. ...