CEMS comparative study of laser deposited and thermally evaporated Fe/Al multilayers

CEMS Study of the Interface Formation in the Fe-Si System during Pulsed Laser Deposition

“…Recently, it has been shown [4,8], that when using PLD techniques the interfaces produced upon deposition of Fe onto Si (henceforth denoted as Fe/Si) or of Si onto Fe (Si/Fe) have different thickness, presumably due to the different energy distributions of the Fe and Si fluxes. Analogous investigations for the Fe±Al system have been reported in [7] where the PLD interface structures were shown to be different from those formed by A. Zenkevitch et al: CEMS Study of the Interface Formation in the Fe±Si 279 thermal evaporation. In the PLD process the energy of the emitted atoms depends critically on the irradiance (power density) of the ablating laser flux.…”

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

“…Our results definitely exclude such an interpretation. The M€ ossbauer study of Geilman et al 5 The observed large interface asymmetry can originate from the difference of several physical parameters; mostly, the role of the energy barriers for surface diffusion and incorporation processes, and the local acceleration mechanism has been emphasized. [11][12][13] Recent MD studies suggested the role of the atomic size and mass difference in the asymmetric behavior of some other bilayer systems on the course of energetic bombardments.…”

“…The Fe-Al system is selected for this purpose since the largely different chemical mixing at the top and the bottom interface has been established by different experimental methods. [2][3][4] The interface mixing in Fe-Al multilayers has been studied intensively by MS, [5][6][7][8][9][10] as well, and due to the outstanding properties of the alloy system for industrial applications, the M€ ossbauer parameters of the different alloy phases and the dependence of the hyperfine fields (HFs) on the number of Al neighbors in the bcc phase are well studied. 8 MD simulations have already been performed for the Fe(001)/Al (Al on top of Fe) and Al(001)/Fe (Fe on top of Al) interfaces, 11,12 and these indeed show an asymmetry of the top and bottom Fe interfaces.…”

“…In M€ ossbauer spectroscopy, the top and the bottom interface of a Fe layer has generally been distinguished by the 57 Fe marker method, 5,14,15 in which case the position of a thin 57 Fe layer (the M€ ossbauer isotope) is varied across the natural Fe layer. The application of this method is limited by the possible mixing and diffusion between the 57 Fe marker and the natural Fe layers, and in case of an extended interface, the quantitative conclusion is difficult.…”

Structural evolution of Fe-Al multilayer thin films for different annealing temperatures

“…It is known that the Al solubility in Fe is much higher than the Fe solubility in Al: at room temperature, Al can be dissolved up to 20 at.% in α-Fe, whereas the solubility of Fe in Al is lower than 0.04 at.% [1]. Geilman et al [24] in a CEMS analysis of Fe/Al multilayers deposited by thermal evaporation observed that the interface layer, a few nm thick, consisted of a structured region composed of a paramagnetic phase of approximately Fe:Al = 1:1 atomic composition and a solid solution of Al in Fe, presumably with a strong Al concentration gradient. By observing the increased intensity of the central component in the CEM spectrum of the sample annealed at 473 K, figure 2, we deduce that the atomic mixing is appreciable even for low-temperature treatment.…”