Combined ferromagnetic and mechanical properties of Fe₃₂Co₄₄Hf₁₂N₁₂ / TiN multilayer coatings for high frequency sensor applications

K. Krueger, M. Stueber, K. Seemann, H. Leiste, S. Ulrich

Kathrin.krueger@kit.edu

Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Nowadays, as the state of the art, wear resistant coatings are used to extend the lifetime of mechanical components like, e.g., bearings or tools.

As a new concept, we combine hardness with magnetic properties within a thin film multilayer system which consists of hard and ferromagnetic interface layers, in order to simultaneously develop and tailor the mechanical and magnetic properties. This multilayer acts as a wear resistant coating, and due to the embedded ferromagnetic material it is possible to monitor an in situ temperature or strain induced stress which changes the magnetic properties like high frequency response.

We present the investigations of a new Fe₃₂Co₄₄Hf₁₂N₁₂ / TiN multilayer system with regard to its hardness and ferromagnetic high frequency properties in comparison to Fe₃₂Co₄₄Hf₁₂N₁₂ and TiN single layers, in order to obtain an appropriate sensor material. It will be shown that the material selection and the specific multilayer design provide good magnetic softness (µ₀H_c < 1.3 mT) and cut-off frequencies above 2 GHz. Additionally, low residual stresses and high hardness values, similar to the hardness of TiN, can be achieved.