Using magnetic structure of Co40Pd60/Cu for the sensing of hydrogen

This paper reports on a magnetic device with a [Co40Pd60/Cu]10/Fe structure for use in the detection of H2. In a magneto-optical, transport, and gas-detection system, the proposed device presented sharp, reproducible H2-dependent magnetic/electrical properties. The device's saturation magnetization (induced resistance change) dropped (increased) by a factor of ∼5 when a H2 pressure of 75 kPa is given. Besides, the electrical signal-to-noise ratio of the device can be restored ∼50% by exposing it to a magnetic field of 1000 Oe, even when the sensitivity of the device dropped at a low H2 pressure (0.7 KPa). This demonstrates the applicability of the device for use as a low-pressure H2 detector. Operando x-ray spectroscopy revealed that changes in H2-induced magnetism arose from a Co-Pd charge transfer effect coupled to changes in the local-structure symmetry.