Probing and Controlling Dopant Distribution in Dilute Magnetic Semiconducting Nanocrystals

Precise control of magnetic dopant distribution in semiconductor nanocrystals (NCs) is essential for advancing spintronic and magneto-optical technologies. In dilute magnetic semiconductors (DMS), uncontrolled clustering disrupts sp–d exchange, reduces spin coherence, and limits device performance. Here, we present a synthesis strategy to engineer Co and Pt dopants in CdS NCs into either clustered or uniformly diffused configurations. Magnetic circular dichroism spectroscopy directly correlates dopant distribution to magneto-optical response, showing that uniform diffusion yields stronger Zeeman splitting, enhanced sp–d coupling, and higher magnetic anisotropy than clustered systems. Co–Pt codoping further amplifies performance via spin–orbit coupling and 3d–5d hybridization. These results establish dopant spatial control as a practical design lever for tailoring magneto-optical properties, enabling high-sensitivity quantum sensors, magneto-optical modulators, polarization-selective detectors, and integrated spin–photonics. By bridging precision synthesis with functional metrics, this study provides design principles for translating DMS nanomaterials into next-generation spintronic and quantum photonic applications.