The kinematics of hydrogen diffusion in nontransparent metallic materials is crucial to the hydrogen-sensing and -storage technology and remains a challenge. Alongside the conventional optical investigations, the hydrogen absorption-induced reversible changes of magnetic properties in ferromagnetic thin films provides a new method for visualization of hydrogen in solids. Here we monitor real-time hydrogen diffusion in a cobalt-palladium alloy (Co₂₅Pd₇₅) film using a magneto-optical Kerr microscope. The spatially resolved magneto-optical contrasted images provide a noninvasive method of monitoring hydrogen movement. Hydrogen diffusion follows Fick’s diffusion law, and a diffusion coefficient of 3 ± 2 × 10⁻¹² m²/s is obtained. The diffusion velocity of the 2–4% hydrogen concentration fronts reaches 30 ± 15 nm/s in the uniform film area and increases to 50 ± 20 nm/s near a defect site. These results can be applied in detecting hydrogen diffusion in other spintronic materials, such as magnetic palladium-alloy thin films.

氢在不透明金属材料中扩散的运动学对氢感测和存储技术至关重要，并且仍然是一个挑战。除了常规的光学研究外，氢吸收引起的铁磁薄膜中磁性的可逆变化提供了一种可视化固体中氢的新方法。在这里，我们使用磁光Kerr显微镜监测钴-钯合金（Co ₂₅ Pd ₇₅）膜中的实时氢扩散。空间分辨的磁光对比图像提供了一种监测氢运动的非侵入性方法。氢的扩散遵循菲克扩散定律，扩散系数为3±2×10 ^-12  m ²/ s已获得。2-4％氢浓度前沿的扩散速度在均匀膜区域中达到30±15 nm / s，并在缺陷部位附近增加至50±20 nm / s。这些结果可用于检测氢在其他自旋电子材料中的扩散，例如磁性钯合金薄膜。