Magnetic media patterned by laser interference lithography

The scope of this thesis consists on the fabrication and magnetic characterization of CoNi/Pt and Co/Pt patterned films with perpendicular anisotropy with possible applications as an information storage medium. We have realized patterned magnetic nanodots arranged in square and hexagonal lattices with periodicites ranging from 600 nm down to 300 nm, which corresponds to bit densities from 1.8 Gb/sqi up to 7.2 Gb/sqi. The main aim has been focused towards the understanding of the problems involved in the fabrication of large samples (1 × 1 cm till 3 × 3 cm) and their write-ability. We discuss about the magnetic properties of an idealized magnetic pattern medium. Issues as the thermal stability, required magnetic anisotropy, bit to bit interaction and its consequences for the material’s switching field distribution are considered. Laser Interference Lithography has been the technique chosen to produce the patterned media samples studied in this work. A discussion about different photoresist stacks which were used in the course of this work is presented. We also discuss on the etching process and the photoresist removal afterwards. Regarding the magnetic analysis of the samples, three issues are mainly discussed: The possible damage to the magnetic properties of the material due to the fabrication process, in particular the ion beam etching step and the subsequent removal of the residual photoresist. The switching field distribution displayed by the samples and possible ways to reduce it are also discussed. Finally we examine the thermostability of our samples. Difficulties in writing and retrieving actual information are commented and possible lines for further research are sketched.