Probing Radical-Induced Magnetic Moment Modulation at Cobalt Interfaces via Soft X-Ray Photoelectron Spectroscopy

We investigate the influence of the deposition of a Blatter-pyr radical layer on polycrystalline cobalt using X-ray photoelectron spectroscopy (XPS), treating the full interface as a hybrid system. Our analysis reveals a chemical bond between the radical layer and cobalt surface, resulting in the loss of radical character upon deposition. Despite this, the chemisorption process effectively modulates the cobalt magnetic moment, which decreases to 1.53 μ_B, consistent with recent findings in organic closed-cell systems. These results highlight the sensitivity of XPS in detecting subtle electronic and chemical changes at metal/radical interfaces and emphasize the role of interfacial bonding in tuning magnetic properties. While the study focuses on interfacial magnetism rather than preserving molecular spin, future strategies may involve designing molecules with selective anchoring groups to maintain radical integrity. Measurements were conducted at room temperature without external magnetic fields, underscoring the practicability of the approach. Given the experimental challenges in probing such hybrid systems, our method offers a versatile and accessible pathway for identifying organic/ferromagnetic interfaces with promising spintronic potential.