Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

Abstract

The chemical mixing at the "Al on Fe" and "Fe on Al" interfaces was studied by molecular dynamics simulations of the layer growth and by 57 Fe M€ ossbauer spectroscopy. The concentration distribution along the layer growth direction was calculated for different crystallographic orientations, and atomically sharp "Al on Fe" interfaces were found when Al grows over (001) and (110)

Asymmetric alloy formation at the Fe-on-Ti and Ti-on-Fe interfaces

“…Our MD simulation results on interface mixing are in good agreement with the above expectations. It is worth a mention that the MD simulations provided a much larger asymmetry for the Fe-Al system [17] in accordance with the surface energy values, being smaller for Al (1.14-1.16 (J m −2 )) than for Ti. The cohesive energy is also smaller for Al than for Ti [39], thereby making Al-for-Fe exchanges easier at the Al surface than Ti-for-Fe exchanges at the Ti surface.…”

“…The FeTi cross-interaction was taken into account by the Johnson mixing rule [29] which provides reasonable alloy properties. Further details of the simulated thin film growth can be found in [17].…”

“…Samples were prepared using iron metal highly enriched in the 57 Fe Mössbauer resonant isotope. In order to determine the phase fractions within the top (Ti-on-Fe) and bottom (Fe-on-Ti) Fe interface Ti/ 57 Fe/ Ti and Ag/ 57 Fe/Ti sample pairs were compared exploiting the non-mixing property [16,17] of Fe and Ag. Analysing the spectra of Ag/ 57 Fe/Ti samples provides information on the Fe-on-Ti interface, since the Ag/Fe interface is indeed chemically sharp and the Ag layer causes only a small and well documented change [18] in the hyperfine parameters of 57 Fe within the atomic layers nearest and next-nearest to the Fe-Ag interface.…”

High Tunneling Magnetoresistance in Magnetic Tunnel Junctions with Subnanometer Thick Al2O3 Tunnel Barriers Fabricated Using Atomic Layer Deposition

“…Based on the literature, negligible intermetallic formation between the Nb/ Fe or Fe/Al structure is anticipated. 45,46 As Al is not FM and the paramagnetic moment for the very thin (7 nm) Al layer, as opposed to that for the 50 nm FM Fe layer, is negligible, the comparable M−H loops for the Nb (50 nm)/Fe (50 nm) and Nb (50 nm)/Fe (50 nm)/Al (7 nm) samples are anticipated. Figure 1b shows the M−H loops of both 50 nm (black and red) and 5 nm (purple and blue) thick Fe films, and the overlap of the M−H loops for the samples of the same thickness illustrates reliable reproducibility from run to run.…”