Fluorescence extended X-ray absorption fine structure analysis of half-metallic ferromagnet 'zinc-blende CrAs' grown on GaAs by molecular beam epitaxy

摘要

In this work, geometric structures for a half-metallic ferromagnet "zinc-blende CrAs", which showed ferromagnetic behavior beyond room temperature, were investigated using fluorescence extended X-ray absorption fine structure (EXAFS) measurement. The EXAFS measurements revealed that As atoms around Cr atoms in the 2 nm CrAs film grown on a GaAs(001) substrate were coordinated tetrahedrally, indicating formation of zinc-blende CrAs. The Cr-As bond length in the zinc-blende CrAs is 2.49 A. This value is close to that which was estimated from the lattice constant (5.82 A) of ferromagnetic zinc-blende CrAs calculated by full-potential linearized augmented-plane wave method. The EXAFS analysis show that the theoretically predicted zinc-blende CrAs can be fabricated on GaAs(001) substrate by low-temperature molecular-beam epitaxy.