Lorentz Transmission Electron Microscopy Image Simulations of Experimental Nano-Chessboard Observations in Co-Pt Alloys.

The magnetization configuration of a novel nano-chessboard structure consisting of L10 and L12 phases in a Co40Pt60 alloy is investigated using Lorentz transmission electron microscopy (LTEM) and micro-magnetic simulations. We show high-resolution LTEM images of nano-size magnetic features acquired through spherical aberration correction in Lorentz Fresnel mode. Phase reconstructions and LTEM image simulations are carried out to fully understand the magnetic microstructure. The experimental Fresnel images of the nano-chessboard structure show zig-zag shaped magnetic domain walls at the inter-phase boundaries between L10 and L12 phases. A circular magnetization distribution with vortex and anti-vortex type arrangement is evident in the phase reconstructed magnetic induction maps as well as simulated maps. The magnetic contrast in experimental LTEM images is interpreted with the help of magnetic induction maps simulated for various relative electron beam-sample orientations inside the TEM.

Thin film compressive stresses due to adatom insertion into grain boundaries.

Atomic simulations of the growth of polycrystalline Ni demonstrate that deposited atoms incorporate into the film at boundaries, resulting in compressive stress generation. Incorporated atoms can also leave the boundaries and thus relieve compressive stress. This leads to a complex interplay between growth stress, adatom incorporation, and surface structure. A simple, theoretical model that accounts for grain size effects is proposed and is in good agreement with simulation results.