Growth mode, magnetic and magneto-optical properties of pulsed-laser-deposited Au/Co/Au(111) trilayers

Abstract

International audienceThe growth mode, magnetic and magneto-optical properties of epitaxial Au/Co/Au(111) ultrathin trilayers grown by pulsed-laser deposition (PLD) under ultra-high vacuum are presented. Sapphire wafers buffered with a single-crystalline Mo(110) bilayer were used as substrates. Owing to PLD-induced interfacial intermixing at the lower Co/Au(111) interface, a layer-by-layer growth mode is promoted. Surprisingly, despite this intermixing, ferromagnetic behavior is found at room temperature for coverings starting at 1 atomic layer (AL). The films display perpendicular magnetization with anisotropy constants reduced by 50\% compared to TD-grown or electrodeposited films, and with a coercivity more than one order of magnitude lower ($\lesssim$ 5 mT). The magneto-optical (MO) response in the low Co thickness range is dominated by Au/Co interface contributions. For thicknesses starting at 3 AL Co, the MO response has a linear dependence with the Co thickness, indicative of a continuous-film-like MO behavior

Magnetization reversal dynamics in Au/Co/Au(111) ultrathin films: Effect of roughness of the buffer layer

“…The values of K 1eff are almost twice smaller than the literature value of about 5 Â 10 5 J/m 3 for 1 nm Co thickness [10]. We also note that the anisotropy decreases going to smaller thicknesses, in contrast to the general observations for Au/Co/Au systems of a linear increase of the anisotropy upon decreasing the cobalt thickness, irrespective of the deposit technique used [15][16][17]. However, the reduction of the anisotropy for low (t Co o1 nm) thicknesses was already observed for Pt/Co/Pt systems [18].…”

“…Our coercivity values are slightly lower than the ones reported in the literature for similar systems [6,7,10]. Let us note that the coercivity of truly epitaxial layers can be a few mT only [15]. Magnetic anisotropy being an important ingredient for coercivity let us discuss the anisotropy of our samples.…”

“…In the work of Ref. [15] performed on ultrathin Au/Co/Au layers (1-5 atomic layers) prepared on Mo/Alumina by pulsed-laser deposition (PLD), the surface of the Au buffer layer is atomically flat contrary to the buffer layer of our samples. The highest anisotropy for these samples was found for very low thicknesses, whereas the coercivity did not depend much on the cobalt thickness but was slightly higher for the lowest thickness.…”

“…[10,15] and ours is the morphology of the gold buffer layer. This morphological difference, which obviously affects the cobalt layers, explains the difference in coercivity and anisotropy for the thinnest layers.…”

The Thermal Oxidation Effect of the Single Crystal Silicon (100) on the Magnetic Properties of Ultra-Thin Films of Cobalt.

“…Our coercivity values are slightly lower than the ones reported in the literature for similar systems [2,10,11]. Let us note that the coercivity with few mT only was reported [12]. The values of in table 1 are almost twice smaller than the literature value [2] and we allotted this to the effect of the morphology of the Au buffer layer [4,9].…”