Growth of self-organized nanosized Co pillars in Au(111) using an alternating deposition process

Nanosized Co pillars were grown in Au(111) using a novel deposition process . Starting from a self-organized array of Co dots on the Au(111) surface, w e alternatively deposit Au (0.9 ML) and Co (0.1 ML). Under appropriate cond itions, the newly deposited Co atoms assemble into dots, vertically self-al igned and in direct contact with the Co dots from the previous layers. This way, pillars 8 nm high and with a 2:1 vertical aspect ratio were fabricate d. It is argued that the growth process is driven by parameter misfit and s urface energy effects, and should thus occur for other pairs of elements th an (Co,Au). From the superparamagnetic regime, we deduce that each pillar b ehaves like a single magnetic entity. The onset of perpendicular remanence occurs around room temperature, instead of 20 K for the initial flat dots. In terms of applications, the main drawbacks of self-assembled and organize d nanosized magnetic systems are the small amounts of material contributing to magnetic effects, and the superparamagnetism blocking temperature, gene rally well below RT. The pillar growth process is a good candidate to solve them simultaneously. (C) 2000 Elsevier Science B.V. All rights reserved.