Prof. Dr. D. Pescia

Laboratorium für Festkörperphysik, ETH Zuerich

We grow laterally patterned ultrathin magnetic films by using a shadow MBE deposition technique. With this method, ultrathin dots with any shape and size can be produced as single elements.

Lateral engineering can be used for many purposes. For instance, we have applied lateral engineering to study the phase transition of perpendicularly magnetized fcc Fe ultrathin films on Cu(100). We find that the system consists of stripes with "up" and "down" magnetization. The disordering of the stripe phase occurs in two steps, reminescent of a Kosterlitz-Thouless-Nelson-Halperin two-dimensional melting process.

As an other example, we have studied the stability of ultrathin dots against domain formation. We define a similarity operation that projects a dot of any shape with length "one" to a dot with the same shape but with length "L". This operation establishes a scaling behaviour of the energies

relevant to domain formation, which can be determined exactly and analytically. By lateral patterning, the very same similarity operation can be realized experimentally as well. We find that in-plane magnetized dots obey a no-domain rule, while perpendicularly magnetized dots show a multi-domain to single-domain transition when their lateral size is reduced below a critical scale. Both experimental observations are in agreement with our exat results.