Dual-Layer Anomalous Hall Effect Sensor for Enhanced Accuracy and Range in Magnetic Field Detection

This study introduces a method aimed at enhancing both the accuracy and the range of magnetic field sensors, which are two critical parameters, in a novel NiCo₂O₄-based anomalous Hall effect sensor. To fine-tune the linear range of the sensor, we introduced epitaxial strain using a MgAl₂O₄ cover layer, which significantly influenced the strain-modulated magnetic anisotropy. A NiCo₂O₄/MgAl₂O₄/NiCo₂O₄/MgAl₂O₄ heterostructure was further constructed, achieving differentiation in the material characteristics across both upper and lower NiCo₂O₄ layers through the modulation of thickness and strain. A dual-layer Hall bar was designed to enhance the integration of the sensor, offering varied detection ranges. This approach enabled the realization of ultrahigh sensitivity, measuring 10,000 V/(AT) within a ±0.1 mT range, and a competitive sensitivity of 60 V/(AT) within a ±5 mT range. By reducing the thickness of the top NiCo₂O₄ layer, an ultra-wide measurement range of ±1000 mT was also achieved. These results highlight the considerable promise of NiCo₂O₄-based anomalous Hall effect devices as compact, multi-range tools in the domain of magnetic sensing technology.