Nano-patterning of magnetic anisotropy by controlled strain relief

In the highly strained system Fe/W(001) the formation of parallel dislocati on bundles upon nucleation of fifth layer islands is used to locally break the fourfold symmetry. The uniaxial strain relief in the dislocation bundle s introduces strong uniaxial in-plane magnetic anisotropies. By controlling the density of fifth layer islands local magnetic anisotropies are structu red on the nanometer scale. As a result of this patterning of anisotropies, the magnetic properties of the films are drastically altered. As a functio n of the pattern size, the coercivity of the films can be varied in a contr olled way over more than two orders of magnitude without changing the film thickness. For pattern sizes larger than the estimated domain wall width, M OKE and micromagnetic calculations indicate the break-up of the film into m agnetic in-plane structures on the 100 nm scale.