Hydrogen-induced spin reorientation in [Co/Pd]₈ multilayers: A comparative study with magnetic and 2D-hBN capping layers

This study investigates the modulation of magnetic anisotropy and spin-reorientation transitions (SRT) in [Co/Pd]₈ multilayers through nanoscale interlayer engineering, with a focus on the role of hexagonal boron nitride (hBN) and Pd/Fe capping layers. By introducing hBN as a 2D spacer, the intrinsic magnetic properties of both in-plane magnetized Fe and perpendicularly magnetized [Co/Pd]₈ are preserved, effectively suppressing electronic hybridization and exchange coupling. In contrast, direct contact between Fe and [Co/Pd]₈ leads to mutual anisotropy suppression and heightened sensitivity to hydrogen-induced SRT. Furthermore, hBN serves as a surface barrier that delays Pd-catalyzed hydrogen dissociation, modulating the onset of magnetization reorientation. Comparative experiments reveal that Pd/Fe capping accelerates SRT at lower hydrogen pressures, while hBN coverage stabilizes magnetic domains and delays transition thresholds. These effects are attributed not only to hBN’s role as an electronic spacer and surface barrier, but also to its atomically thin, van der Waals-bonded structure, which minimizes interfacial strain and charge transfer. This highlights the potential of 2D materials—beyond classical insulators—in tailoring magnetic responses for spintronic applications and hydrogen-sensitive magnetic devices.