Stabilization of bcc Co via Epitaxial Growth on GaAs

A new metastable phase of cobalt—body-centered cubic—has been synthesized by use of molecular-beam epitaxial growth to stabilize the crystal structure. Large (1×1 ${\mathrm{cm}}^2$) films have been grown on (110) GaAs and characterized by high-energy electron diffraction, Auger analysis, x-ray diffraction, magnetometry, spin-polarized photoemission, and ferromagnetic resonance. The results indicate a ferromagnetic material very similar to $\alpha$-Fe both electronically and magnetically, with a metastable lattice constant $a_0=2.827\mathrm{}$ Å. This technique provides a general approach for the realizing of metastable phases.