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Debakel, fiasco, mislukking. Het zijn dagelijkse bezigheden voor ons onderzoekers. Je kan er dus maar beter mee leren omgaan. Veel mensen hebben zich uitgesproken over hun tevredenheid met mislukkingen. Bijvoorbeeld Albert Einstein’s “Anyone who has never made a mistake has never tried anything new.‿ Robert Oppenheimer leert ons dat we er juist trots op moeten zijn, want “Any man whose errors take ten years to correct is quite a man.‿ Je kan het ook te bont maken, dus opgepast. “Only a fool learns from his own mistakes. The wise man learns from the mistakes of others,‿ aldus Otto von Bismarck. Het inzetten van studenten op kansarme idee¨en lijkt dus een goede oplossing.

Dit verhaal gaat over doorslaan. Het vertelt iets technisch over doorslag in veldemissie, maar vooral hoe een promotie-onderzoek een promovendus tot wanhoop kan drijven, en hoe een begeleider voorkomt dat hij doorslaat. Het begint allemaal bij de hard disk. Dat is een mechanisch geadresseerd geheugen, net als de DVD of tape. Er zijn ook elektrisch geadresseerde geheugens zoals RAM en vooral FlashMemory. De snelle opmars van Flash is fascinerend, maar was eigenlijk voorspelbaar. Maar zo gaat het vaak: als voorspellingen werkelijkheid worden, zijn we iedere keer weer verbaasd.

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.

We describe the design rationale for a hardware tamper resistant secure storage system based on probe storage with a patterned magnetic medium. This medium supports normal read/write operations by magnetising individual dots perpendicular to the media plane. We report on an experiment to show that in principle the medium also supports a separate class of read/write-once operations by allowing individual dots in the media to be destroyed irreversibly by precise local heating. Security stems from the fact that bulk-erase is not possible.