Speaker
Description
Magnetoresistive magnetic sensors play a key role in sensing magnetic fields at room temperature, with applications spanning from information storage to biomagnetism. Extraordinary magnetoresistive (EMR) sensors are a promising class of magnetoresistive sensors, which exhibit a magnetoresistance on the order of $7.5\times 10^5\,\%$ at 4T [1]. The extraordinary magnetoresistance is a geometrical effect arising from a field-dependent change in the current paths in devices consisting of two materials with different conductivities. As the effect is very sensitive to the device's geometry, finite element simulations are often used to optimize and predict the performance prior to sensor fabrication. In simulations, however, EMR devices are often assumed flat, unlike real devices, where deposition techniques often result in devices with significant topography.
Here, we consider this topography explicitly by numerically studying metal-semiconductor EMR devices with different 3-dimensional topographies. We vary the geometry of the inner metallic region such as its height and sidewall width because such topographies are usually realistic in sensor production. We show that modeling the 3-dimensional geometry of the EMR sensor is important for capturing the experimental data, as our 3-dimensional numerical model results in good agreement with experimental data [1], exhibiting a low relative error of 4.5 $\%$ for the resistance at 0 T. When using traditional 2-dimensional geometries, this error evaluates to a significantly higher 35.8 $\%$. In addition, we present pathways for both simplifying device fabrication and enhancing the magnetoresistance by making active use of the third dimension.
Acknowledgements
We acknowledge the support of Novo Nordisk Foundation Challenge Programme 2021: Smart nanomaterials for application in life-science, BIOMAG Grant NNF21OC0066526.
References
[1] S. A. Solin, T. Thio, D. R. Hines, and J. J. Heremans, “Enhanced Room-Temperature Geometric Magnetoresistance in Inhomogeneous Narrow-Gap Semiconductors,” Science, vol. 289, no. 5484. American Association for the Advancement of Science (AAAS), pp. 1530–1532, Sep. 2000. doi: 10.1126/science.289.5484.1530.
