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The coarsening of the two-phase, bi-continuous microstructure via surface diffusion is simulated using a three-dimensional Monte Carlo (MC) model. The coarsening exponent obtained from simulations initially decreases and then saturates at ~4 as the temperature increases. Kinetic analysis on nanoporous gold (np-Au) samples, annealed at 450 and 600 °C, confirms the prediction of the model. The coarsening probability ratio of np-Au between two annealing temperatures, calculated from the reported activation energy for coarsening of np-Au, is comparable to that of the model, signifying that the simulation successfully mimics the kinetic evolution of the thermally coarsened np-Au via surface diffusion.

We explore the optimal condition for cylindrical core/shell hard-soft exchange-coupled magnetic nanostructures by obtaining full hysteresis loops for various geometries by obtaining full hysteresis loops for various geometrical variables, including the dimensional scale and soft/hard-magnetic phase volume ratio through micromagnetic simulations. For achieving maximum energy product (BH), it is essential to increase the demagnetizing field by increasing the volume fraction of the soft magnet while maintaining a positive nucleation field and, which can be possible by the scaling-down. To scale up the nanostructure to a bulk magnet having high BH can be achieved by forming an array of needle-shaped exchange-coupled cylinders. These findings could lead to the flexible design and scalable fabrication of exchange-coupled permanent magnets.