Supersoft Transition Metal Silicides

Candidates for epitaxially stabilized structures of Fe, Co, and Ni silicides are searched by ab initio calculations. We find that the pseudomorphic phases of ${\mathrm{FeSi}}_2$ in the $C1\mathrm{}$ structure and CoSi and NiSi in the $B2\mathrm{}$ structure soften dramatically under compressive biaxial strain induced by epitaxy on a (100) substrate. This supersoft effect is reflected by zero strain energy, constant volume, and constant bond energies.