Functional layers

Head: Dr. Klaus Seemann

Soft magnetic, thin layers for high-frequency applications down to the lower GHz range are produced as single-layer or multilayer coatings using the PVD magnetron cathode sputtering process with layer thicknesses of up to a few micrometers. The material selection of the layers is carried out, among other things, under the aspect of thermal stability. The layer properties required for high-frequency suitability (e.g. uniaxial anisotropy in the layer plane) are imprinted at temperatures between 400 °C and 600 °C in a static magnetic field. Fe-Co-Re-NM composites with Re=refractory elements (e.g. Ta, Hf, Zr) and NM=non-metals such as nitrogen (N) serve as material basis. The work covers fundamental as well as application-oriented research activities in the field of high-frequency magnetism of single and multilayer coatings, e.g. in the field of sensor technology. Measuring stations for the determination of the magnetization (VSM, MOKE) and the high-frequency behavior (RF permeameter) for the magnetic and high-frequency characterization of the layers up to the GHz range are available. The work is underpinned by theoretical models.

Complex frequency-dependent permeability of a Fe-Co-Hf-N film and computed precession trajectory of the magnetic moment.

In-plane polarisation curves of a Fe-Co-Hf-N film in its easy and hard direction of polarisation.

Dark field image (TEM) and diffraction diagram of an Fe-Co-Hf-N film.

Bright field image (TEM) of a FeCo (20nm) / TiN (63nm) multilayer film.