SUPERSOFT TRANSITION-METAL SILICIDES

Candidates for epitaxially stabilized structures of Fe, Co, and Ni sil icides are searched by ab initio calculations. We find that the pseudo morphic phases of FeSi2 in the C1 structure and CoSi and NiSi in the B 2 structure soften dramatically under compressive biaxial strain induc ed by epitaxy on a (100) substrate. This supersoft effect is reflected by zero strain energy, constant volume, and constant bond energies.