Influence of dopant concentration on the phase stability and magnetism of diluted magnetic semiconductors

This study investigates how dopant concentration influences phase stability and magnetic behavior in diluted magnetic semiconductors (DMS). Using a series of metal-chalcogenide and oxide host matrices doped with transition-metal ions (Mn, Co, and Fe) across a wide concentration range (0.5-15 at.%), we combined controlled synthesis (solid-state reaction and pulsed-laser deposition), structural characterization (X-ray diffraction, transmission electron microscopy), chemical/valence analysis (XPS, EELS), and magnetic/electronic measurements (SQUID magnetometry, Hall effect, and temperature-dependent resistivity). We find a clear concentration-dependent evolution: at low dopant levels (