Strain-induced tetragonal distortions in epitaxial Ni-films grown on Cu(001)

The structural and magnetic properties of thin Ni films epitaxially grown on Cu(001) substrates have been investigated using ab-initio local-spin-density calculations in the generalized gradient approximation. We show that the lattice mismatch at the Ni-Cu interface induces a tetragonal distortion of the Ni-films of about 6%, superposed at the free surface by an inward relaxation of the Ni top-layer which is slightly larger than in bulk fcc Ni(001). The magnetic moments of the Ni atoms are enhanced at the free surface, but reduced at the Ni-Cu interface relative to the value in bulk Ni. The effect of the surfactant Cu layer is examined and it is shown that this effect can account for the existing discrepancies between calculated and measured structural features of thin Ni films. Π2000 IOP Publishing Ltd.