Magnetic transition phase diagram of cobalt clusters electrodeposited on HOPG: Experimental and micromagnetic modelling study

Complementary atomic force microscopy and magnetic force microscopy study for the magnetic transition of cobalt clusters onto gold substrates

“…The clusters formation was achieved with the potential step technique from +600 mV towards different reduction potential values (−820 mV, −840 mV, −860 mV, −880 mV) for 32 seconds, in order to investigate the clusters magnetic evolution at different formation stages. From previous experience with this electrochemical system, a diffusional 3D growth was observed [26].…”

“…In order to represent the experimental size and shape of the clusters as seen with AFM, the simulations where performed on oblate ellipsoids up to 80 nm in height and base diameters up to 800 nm. The simulations were carried out in the presence of a uniform external magnetic field (380 mT) applied along the z direction, to simulate the presence of the magnetic tip in order to reproduce the out-of-plane magnetic component in the MFM images [26]. The cluster mesh was 2.0 nm, which was below the calculated exchange length value of 2.7 nm by using [31] and A = 1.1 × 10 −11 J/m [32].…”

“…For instance, magnetic force microscopy has become an essential technique to characterize the magnetic stray field distri-bution of clusters and thin films with an unprecedent spatial resolution. In recent works, the local magnetic stray field of independent cobalt clusters electrodeposited from sulfate solutions onto ITO [22], HOPG [26] and Si [27] was correlated with the height and diameter of the clusters. Here, a clear dependence on the height rather than the diameter of the clusters was observed for the transition from the single to the multi domain magnetic state.…”

Electrodeposition of Cobalt Nanoclusters From Ammonical Chloride Solutions Onto Hopg Electrodes. A Kinetical and Morphological Study

“…However, a good knowledge of the kinetic parameters involved during the electrodeposition process is required to achieve a precise control of the cobalt nanoclusters synthesis. In this sense, sulfate solutions have been the preferred systems to electrodeposit cobalt nanoclusters, [24][25][26][27][28][29][30] Although chloride solutions are widely employed for studying the cobalt electrochemistry, these plating baths have been scarcely used to electrodeposit cobalt nanoclusters. Probably, it is because chloride ions induces stress on the cobalt deposited, 31 and may interact strongly with Co adatoms yielding drastic changes on the deposit morphology.…”

“…In this sense, sulfate solutions have been the preferred systems to electrodeposit cobalt nanoclusters, [24][25][26][27][28][29][30] onto stainless steel, 24 thin niobium films, 25 aluminium, 26 graphene, 27 copper, 28 and Highly Oriented Pyrolytic Graphite (HOPG) electrodes. 29,30 Although chloride solutions are widely employed for studying the cobalt electrochemistry, these plating baths have been scarcely used to electrodeposit cobalt nanoclusters. Probably, it is because chloride ions induces stress on the cobalt deposited, 31 and may interact strongly with Co adatoms yielding drastic changes on the deposit morphology.…”