Structural variations in strained crystalline multilayers

Abstract

We present a computer simulation study of thin crystalline multilayers constructed from two fcc solids with differing lattice constants and binding energies. Initially the two solids have the same orientation, and the interface is perpendicular to the common [100] direction. We then minimize the energy of the system at zero temperature or equilibrate it at a finite temperature. Both materials are described by Lennard-Jones interatomic potentials. A novel technique for analyzing local atomic ordering, common neighbor analysis, is used to identify structural characteristics in these systems. As we gradually vary the lattice mismatch between the two solids, several structural changes are observed in the layers of smaller atoms after energy minimization. At a mismatch larger than 14%, the layers transform into the hep structure, while at smaller mismatches extended structural defects are generated. At elevated temperatures, the hcp structure is transformed back to fcc, and the structure defects disappear.