Tunable Magnetoresistive Gas Sensing Enabled by La-Deficient LaFeO<sub>3</sub>
Haoming Sun, Congling Yin, J. Paul Attfield, Minghui Yang
Abstract
Resistive sensors are widely used to detect gases, but integrating magnetoresistive effects for enhanced selectivity and sensitivity remains largely unexplored. Here we have investigated several magnetic materials in a metal oxide semiconductor (MOS) sensor, showing that iron oxides can exhibit both positive and negative magnetoresponses at relatively low operating temperatures (120–160 °C), with no simple correlation between magnetoresponse and bulk magnetization, leading to the discovery of La 0.8 FeO 3 as an outstanding material for magnetoresistive gas sensing. Under a 0.9 T magnetic field, La 0.8 FeO 3 shows a 134% increase in response to 40 ppm of NO 2 in air. The paramagnetism of oxygen gas is found to provide a substantial magnetosensing contribution, as the use of nitrogen as the background gas diminishes the magnetoresponse of La 0.8 FeO 3 by a factor of 3. Our findings establish magnetic field modulation as a powerful strategy for tuning gas sensor performance, opening new directions in sensing technologies.