Lattice-Mismatch-Induced Oscillatory Feature Size and Its Impact on the Physical Limitation of Grain Size

Size control of nanocrystals is becoming more crucial in growing, for example, granular ferromagnetic thin films for heat-assisted magnetic recording, or self-assembled quantum dots for quantum computing. This study identifies granular patterns with surprisingly ``quantized'' feature sizes in Fe-Pt thin film grown on lattice-mismatched MgO. This arises from the periodic nature of the misfit-strain energy in such a system; island lengths that are integer multiples of the misfit dislocation period are energetically favored. These results point to synthesizing nanostructured materials with well-controlled grain size by tuning the interlayer lattice mismatch.