Misfit-energy-increasing dislocations in vapor-deposited CoFe/NiFe multilayers

Abstract

Recent molecular dynamics simulations of the growth of ͓Ni 0.8 Fe 0.2 /Au͔ multilayers have revealed the formation of misfit-strain-reducing dislocation structures very similar to those observed experimentally. Here we report similar simulations showing the formation of edge dislocations near the interfaces of vapor-deposited ͑111͒ ͓NiFe/CoFe/Cu͔ multilayers. Unlike misfit dislocations that accommodate lattice mismatch, the dislocation structures observed here increase the mismatch strain energy. Stop-action observations of the dynamically evolving atomic structures indicate that during deposition on the ͑111͒ surface of a fcc lattice, adatoms may occupy either fcc sites or hcp sites. This results in the random formation of fcc and hcp domains, with dislocations at the domain boundaries. These dislocations enable atoms to undergo a shift from fcc to hcp sites, or vice versa. These shifts lead to missing atoms, and therefore a later deposited layer can have missing planes compared to a previously deposited layer. This dislocation formation mechanism can create tensile stress in fcc films. The probability that such dislocations are formed was found to quickly diminish under energetic deposition conditions.

Hidden topological order and its correlation with glass-forming ability in metallic glasses

“…The cooled sample was further relaxed in NVT (constant number, volume, temperature) ensemble for 2 ns at 300 K and 1,000 configurations were extracted from the last 1 ns relaxation for structural analysis such as PCFs. [42][43][44][45] to generate glassy samples. All the simulations were performed using the LAMMPS package 46 .…”

Ploughing friction and nanohardness dependent on the tip tilt in nano-scratch test for single crystal gold

“…shows the friction curves without any tilt (g x ¼ g z ¼ 0 ) by using three sets of EAM potentials [13][14][15]. It can be seen that the change of potential only has small effect on the friction response, the curves fluctuate but the average friction values are converged at the stable stage.…”

“…The Embedded-Atom Method (EAM) potential for Au is taken from Ref. [13], simulations with other EAM potentials [14,15] are also compared in the study. Morse potential between the tip and the substrate is adopted according to Refs.…”

“…, JCP denotes potential [13], U4 denotes potential [14], and Zhou denotes potential [15]. Each curve is averaged over eleven cases as in Table 1.…”

Molecular dynamic simulation of binary ZrxCu100−x metallic glass thin film growth

“…Implementing suitable interatomic potentials is certainly the most important issue in molecular dynamics simulation. For describing the interaction between Zr-Zr, Zr-Cu, Cu-Cu, we use the many-body EAM potential [19][20][21]. Such a potential is non-pairwise in the sense that it is based on concepts coming from density functional theory, which stipulates in general that the energy of a solid is a unique function of electron density.…”