Magnetic Moment Quenching and Spin Texture Formation at Pt/Co/Hf Interfaces.

Interfacial engineering in heavy metal/ferromagnet multilayers is a key approach for tailoring magnetic interactions for spintronic applications. Here, we investigate Pt/Co/Pt multilayers modified by ultrathin Hf spacer layers at the top Co interface. Magnetometry and X-ray magnetic circular dichroism (XMCD) reveal a strong reduction (up to ∼70%) in both the saturation magnetization and the Co atomic magnetic moment with increasing Hf thickness. XMCD further indicates proximity-induced moments in Pt and Hf with opposite alignment relative to Co. Magnetic force microscopy and scanning transmission X-ray microscopy show the formation of worm-like magnetic domains with thickness-dependent length scales. Micromagnetic simulations reproduce the observed domain patterns by introducing an effective Dzyaloshinskii-Moriya interaction, suggesting that interfacial asymmetry and magnetic moment quenching govern the magnetic configuration. These results show that buried spacer layers may provide a route for tuning magnetic properties relevant to spin transport and energy-efficient spintronic devices.