We have grown stoichiometrically identical superlattices comprising a bcc transition metal (V, Cr, Fe) together with the metastable high temperature bcc &dgr;-Mn modification on Ge(001) substrates. Despite identical molecular beam epitaxial growth conditions and identical bulk crystal structures of V, Cr, and Fe with nearly identical lattice parameters, the superlattices show a very different crystallographic behavior. The lattice parameters of &dgr;-Mn are found to be strongly dependent on the thickness of the Mn layers as well as the lattice parameters of the adjacent metals. Therefore, different distortions of the cubic bcc &dgr;-Mn structure can be obtained, ranging from almost cubic structures in V/&dgr;-Mn superlattices to large tetragonal distortions(c/a≈8&percent;)in Cr/&dgr;-Mn superlattices. Nevertheless, we found that the unit cell volume of the &dgr;-Mn modification remains almost constant for thin Mn layers, and that the deduced cubic lattice parameter for &dgr;-Mn (a=2.985Å) significantly differs from previously predicted and published values. This result appears to be of great importance concerning the predicted magnetic properties of &dgr;-Mn. All presented simulations were performed using the refinement programSUPREXwritten by Schuller, Fullerton, and Bruynseraede. ©1997 American Institute of Physics.