Anion effect in Co/Au(111) electrodeposition: structure and magnetic behavior

In-situ scanning tunneling microscopy (STM) and in-situ alternating gradient field magnetometry (AGFM) are used in combination to characterize the structure and magnetic behavior of Co/Au(111) layers electrodeposited from CoSO4 solutions, with anions X = Cl- and SCN- added in amount traces. In the Cl- solution, the 2-D growth process is briefly recalled. In the thiocyanate (SCN-) solution, preliminary observations show that nanometer clusters accumulate on top of a Co underpotential deposition (UPD) monolayer. Both structures solution/Co/Au(111) exhibit perpendicular magnetic anisotropy (PMA) for a Co thickness t less than or equal to t*, with t* similar to 2 ML in the Cl- solution and similar to 4-5 hit in the SCN- one. Results are briefly discussed in light of classical models for PMA in ultrathin films. (C) 2000 Elsevier Science B.V. All rights reserved.