Boundary-induced phase in epitaxial iron layers

We report on the discovery of a boundary-induced body-centered tetragonal iron phase in thin films deposited on MgAl2O4(001) substrates. We present evidence for this phase using detailed x-ray analysis and ab initio density functional theory calculations. A lower magnetic moment and a rotation of the easy magnetization direction are observed, as compared with body-centered cubic iron. Our findings expand the range of known crystal and magnetic phases of iron, providing valuable insights for the development of heterostructure devices using ultrathin iron layers.