Dzyaloshinskii-Moriya interaction in Ni/Cu(001)

Dzyaloshinskii-Moriya interaction (DMI) is found in the epitaxial Ni/Cu(001) system by imaging magnetic domain wall profiles with high resolution and by Brillouin light scattering. The domain walls have right-handed chirality and deviate from both the Néel and Bloch configurations for Ni thicknesses up to 9 nm. From a detailed structural analysis it is found that strain in the Ni film is inhomogeneous with film thickness. We suggest that this strain field is responsible for the symmetry breaking that is required for a sizable DMI to appear, even in absence of a heavy metal.