Ultrathin films of Mn on V{001}: γ- or δ-Mn?

Ultrathin films of Mn grow pseudomorphically on V{001} up to thicknesses of about 15 Å. A quantitative low-energy electron analysis finds the structure of the films to be body-centered tetragonal with a=3.023Å (forced by the V{001} substrate) and c=2.92±0.06Å, with a slightly expanded first-interlayer spacing. Strain analysis (necessary in order to find the equilibrium phase of the films) requires knowledge of the crystallographic and elastic properties of the possible equilibrium phases, which are known only approximately and with large uncertainties, particularly for (bcc) δ-Mn. The available crystallographic data do not allow a confident choice between γ-Mn and δ-Mn as the equilibrium phase of Mn films grown on V{001} (this work) or on Pd{001} or Fe{001} as reported elsewhere.