Atomic ordering in nano-layered FePt

<p>Monte Carlo simulation of chemical ordering kinetics in nano-layered L1<sub style="border: 0px; font-size: 0.75em; margin: 0px; padding: 0px; line-height: 0; color: rgb(46, 46, 46); font-family: 'Arial Unicode MS', 'Arial Unicode', Arial, 'URW Gothic L', Helvetica, Tahoma, sans-serif; text-align: justify; word-spacing: -1px; background-color: rgb(255, 255, 255);">0</sub> AB binary intermetallics was performed. The study addressed FePt thin layers considered as a material for ultra-high-density magnetic storage media and revealed metastability of the L1<sub style="border: 0px; font-size: 0.75em; margin: 0px; padding: 0px; line-height: 0; color: rgb(46, 46, 46); font-family: 'Arial Unicode MS', 'Arial Unicode', Arial, 'URW Gothic L', Helvetica, Tahoma, sans-serif; text-align: justify; word-spacing: -1px; background-color: rgb(255, 255, 255);">0</sub> c-variant superstructure with monoatomic planes parallel to the surface and off-plane easy magnetization. The layers, originally perfectly ordered in a c-variant of the L1<sub style="border: 0px; font-size: 0.75em; margin: 0px; padding: 0px; line-height: 0; color: rgb(46, 46, 46); font-family: 'Arial Unicode MS', 'Arial Unicode', Arial, 'URW Gothic L', Helvetica, Tahoma, sans-serif; text-align: justify; word-spacing: -1px; background-color: rgb(255, 255, 255);">0</sub> superstructure, showed homogeneous disordering running in parallel with a spontaneous re-orientation of the monoatomic planes leading to a mosaic microstructure composed of a- and b-L1<sub style="border: 0px; font-size: 0.75em; margin: 0px; padding: 0px; line-height: 0; color: rgb(46, 46, 46); font-family: 'Arial Unicode MS', 'Arial Unicode', Arial, 'URW Gothic L', Helvetica, Tahoma, sans-serif; text-align: justify; word-spacing: -1px; background-color: rgb(255, 255, 255);">0</sub>-variant domains. The domains nucleated heterogeneously on the surface of the layer and grew discontinuously inwards its volume. Finally, the domains relaxed towards an equilibrium microstructure of the system. Two “atomistic-scale” processes: (i) homogeneous disordering and (ii) nucleation of the a- and b-L1<sub style="border: 0px; font-size: 0.75em; margin: 0px; padding: 0px; line-height: 0; color: rgb(46, 46, 46); font-family: 'Arial Unicode MS', 'Arial Unicode', Arial, 'URW Gothic L', Helvetica, Tahoma, sans-serif; text-align: justify; word-spacing: -1px; background-color: rgb(255, 255, 255);">0</sub>-variant domains showed characteristic time scales. The same was observed for the domain microstructure relaxation. The discontinuous domain growth showed no definite driving force and proceeded due to thermal fluctuations. The above complex structural evolution has recently been observed experimentally in epitaxially deposited thin films of FePt.</p>