XMCD Probing of Spin–Orbit Coupling and Spin Delocalization in Mixed Heavy-Atom Radical Ferromagnets

We propose an X-ray Magnetic Circular Dichroism study of a rare family of metal-free ferromagnets based on pyridine-bridged bisdichalcogenazolyl radicals, including the novel mixed chalcogen (S/Se) systems. This element-specific approach is uniquely positioned to decouple the intertwined roles of chemical substitution, spin-orbit coupling, spin delocalization and chalcogen identity in governing magnetic order. By performing XMCD at the S and Se K-edges across a series of positional isomers, we will directly probe spin delocalization and orbital contributions in these radicals, while field-dependent measurements will be correlated with SQUID data to link microscopic spin distribution with macroscopic magnetic behavior. This study will provide the first atom-resolved insight into the electronic and magnetic structure of mixed heavy-atom radicals, fundamentally elucidating how chemical composition drives magnetic ordering and enabling the rational design of organic magnetic materials.