A widespread approach to gas sensing uses materials whose electrical resistivity changes on exposure to a target analyte. Such conductometric solid-state sensors are versatile and relatively inexpensive, but they typically lack chemical selectivity. This could be changed with sensor materials that show not only an electric but also a strong magnetic response to components of a gas, as Alexander Gerber and colleagues have now demonstrated.
The idea of using changes in magnetic properties for gas detection is not new, but Gerber et al. provide a practical route to exploiting such a concept. Their sensor is based on cobalt–palladium thin films. The material displays a strong extraordinary (or anomalous) Hall effect, brought about by the broken time-reversal symmetry due to spin–orbit coupling. And the alloy dissolves hydrogen. Combine these qualities and the additional magnetic response makes the sensor two orders of magnitude more sensitive for hydrogen than when only changes in electrical conductance are considered, as Gerber and his co-workers showed in a series of experiments, highlighting the promise of complementing conductometric sensing with this spintronic effect.
About this article
Cite this article
Trabesinger, A. Sensor extraordinaire. Nature Phys 13, 1037 (2017). https://doi.org/10.1038/nphys4316