Three-dimensional Monte Carlo simulation of nanorod self-organization in REBa₂Cu₃O_y thin films grown by vapor phase epitaxy

Some metal-complex oxides (MCOs) self-organize within REBa₂Cu₃O_y (REBCO: RE = rare earth) superconducting thin films grown by vapor phase epitaxy. To clarify the self-organization mechanism, we developed a three-dimensional Monte Carlo (3D-MC) simulation code using a simple model and simulated nanorod growth under various growth conditions. As a result, the self-organization of nanorods was reproduced by 3D-MC simulations and we clarified the nanorod growth mechanism as follows. The growth mode of MCO particles was 3D island growth due to the instability of the interface of the MCO and the substrate. On the other hand, that of REBCO particles was 2D island growth. There were diverse nanostructures, which were strongly affected by substrate temperature (Ts) and deposition rate (v_dep). We constructed a contour plot of the nanorod number density and a phase diagram of the nanostructures depending on T_s and v_dep.