Long-range-ordered anodic porous alumina with a reduced hole interval could be obtained by anodization using highly concentrated H2SO4 solutions. The self-ordering of the hole arrangement of alumina occurred at a low applied voltage of 18 V in highly concentrated H2SO4 solution of more than 6 M, which generated long-range-ordered anodic porous alumina with a hole interval of 45 nm. The ordered composite structure of Co/alumina was also fabricated using the obtained long-range-ordered porous alumina.

Metal (Ta) films with ordered structures of nanometer-scale dimensions were fabricated by replicating the structure of a 2D array of ferritin molecules as a template. The deposition of a Ta layer onto a 2D array of ferritin molecules using ion-beam sputtering and subsequent removal of the ferritin molecules generated Ta films with an ordered array of concave with a 13 nm interval. The uniformity and chemical stability of Ta formed by ion-beam sputtering contributed to the precise replication of the fine structures of the 2D array of ferritin molecules.