Selective functionalization of Si(111) and Ag(110) surfaces for preparation of Co nanostructures.

Moyen, Eric1; Macé, Magali1; Léandri, Christel1; Masson, Laurence1; Agnus, Guillaume1; Fleurence, Antoine1; Maroutian, Thomas1; Wulfhekel, Wulf2; Bartelian, Bernard1; Beauvillain, Pierre1; Hanbücken, Margrit1 1France; 2Germany

Dense arrangements of magnetic nanodots and nanowires have been obtained on Si(111) and Ag(110) surfaces. Prior to the growth of cobalt, the substrates have been functionalised in two different ways. On vicinal Si(111), re-arranged into a regular nano-pattern of terraces and step-bunches, two different Au-silicides were grown on the terraces and along the step-bunches respectively. They display different chemical reactivities with cobalt. The selective silicidation of cobalt enables the fabrication of localized magnetic Co-nanodots in the density range of 109 to the low 1012 dots/in2 surrounded by non-magnetic AuCo-silicides. The Ag(110) surface is functionalised with a 5x2 periodic array of silicon nanowires covering the entire surface. The local Co-silicidation is here induced by the alternation of silicon and silver on the substrate leading to the formation of Co-nanowires.
The growth parameters of the described systems and their atomic structures have been studied in situ with scanning tunnelling microscopy. The magnetic properties have been analysed with an alternating gradient force magnetometer.

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