Unraveling the role of magnetic anisotropy on the thermoelectric response: a theoretical and experimental approach

Magnetic anisotropies have a key role in tailoring magnetic behavior in ferromagnetic (FM) systems for specific sensor applications. Furthermore, they are also essential elements for manipulating the thermoelectric response in anomalous Nernst effect (ANE) and longitudinal spin Seebeck effect (LSSE) systems at unsaturated field regimes. Here, we propose a theoretical approach and explore the role of magnetic anisotropies on the magnetization and thermoelectric response of noninteracting multidomain FM systems. The magnetic behavior and the thermoelectric curves are calculated from a modified Stoner-Wohlfarth model for an isotropic system, a uniaxial magnetic system, and for a system with a mixture of uniaxial and cubic magnetocrystalline magnetic anisotropies. The changes in the thermoelectric response caused by the magnetic anisotropy are remarkable. Furthermore, the fingerprints of the energy contributions to the thermoelectric response are disclosed. To test the robustness of our theoretical approach, we engineer films with specific magnetic properties and directly compare experimental data with the theoretical results. Thus, experimental evidence is provided to confirm the validity of our theoretical approach. The results go beyond the traditional reports focusing on magnetically saturated films and show how the thermoelectric effect behaves during the whole magnetization curve. Our findings reveal a promising way to explore the ANE and LSSE as powerful tools for studying magnetic anisotropies, as well as employing systems with magnetic anisotropy as sensing or elements in technological applications.