Paper Title
Hydrogen Sensors using [Co/Pd] N Structure with Perpendicular Magnetic Anisotropy

Abstract
This paper investigates the efficacy of a [Co/Pd]n multilayer device with various degrees of interfacial anisotropy in the detection of H2. Upon exposure to H2, the change in vertical (Rxy) resistivity rate far exceeded that of longitudinal (Rxx) resistivity rate, thereby demonstrating the potential of the proposed Hall device over conventional resistive-type sensors due to a more productive pathway for signal read-out. The magnetic anisotropy of the [Co/Pd]n was found to change from in-plane to out-of-plane with an increase in n (the layer repetition number). This changed the device from one dominated by the ordinary Hall effect (OHE) to that dominated by anomalous Hall effect (AHE), due to enhanced perpendicular anisotropy. The sensitivity of the OHE-dominated device to H2 decreased without an applied magnetic field. The AHE-dominated device retained sensitivity despite field-removal. The proposed devices outperformed current commercial models (solid-state based) in terms of power consumption (< 1mW) by eliminating the need for a heating process. The modularization of the device proved effective when tested using an Arduino prototype-platform. Keywords- hydrogen sensor