La$_2$O$_3$‐Doped ZrO$_2$ Tapes for Enhanced Thermomagnetic Conversion in CoFeB Heterostructures

This work investigates the thermomagnetic response of La$_2$O$_3$-doped ZrO$_2$/CoFeB heterostructures for energy harvesting applications. La$_2$O$_3$-doped ZrO$_2$ ceramic tapes were fabricated via tape casting, followed by the deposition of CoFeB ferromagnetic thin films using magnetron sputtering. This combined approach enabled the realization of hybrid systems exhibiting enhanced thermoelectric performance driven by the anomalous Nernst effect (ANE). Structural characterization by scanning electron microscopy and X-ray diffraction confirmed the formation of La$_2$O$_3$-related phases in the ceramic matrix. Surface polishing improved the ceramic–ferromagnet interface, promoting the growth of soft magnetic CoFeB layers. The thermomagnetic response was evaluated by measuring the ANE under varying thermal gradients and external magnetic fields. The heterostructure with 2% La$_2$O$_3$ doping exhibited the highest performance, with an effective coefficient of 0.26 $\mu$V/K. These results demonstrate the potential of La$_2$O$_3$-doped ZrO$_2$/CoFeB heterostructures for thermomagnetic energy harvesting and highlight the effectiveness of this fabrication route for achieving tunable thermomagnetic responses.