Tunable optical, electronic and magnetic properties of semiconductor nanoparticles induced by magnetic and nonmagnetic dopants: A comparative experimental and theoretical study

Influence of Oxygen Defects and Their Evolution on the Ferromagnetic Ordering and Band Gap of Mn-Doped ZnO Films

“…Figure a displays the room-temperature hysteresis loops of the Zn 1– x Mn x O films with different x values. For the undoped film, the result indicates a typical diamagnetic behavior, as also reported previously. ,, For the doped films, the hysteresis loops indicate that a weak ferromagnetic phase coexists with a paramagnetic (PARA) phase, suggesting different magnetic contributions to the total magnetization. The coexistence of these phases in Mn-doped ZnO was reported by other researchers. ,, The PARA phase is evident by the linear field dependences of the nonsaturated magnetization at the high-field region.…”

“…For the undoped film, the result indicates a typical diamagnetic behavior, as also reported previously. ,, For the doped films, the hysteresis loops indicate that a weak ferromagnetic phase coexists with a paramagnetic (PARA) phase, suggesting different magnetic contributions to the total magnetization. The coexistence of these phases in Mn-doped ZnO was reported by other researchers. ,, The PARA phase is evident by the linear field dependences of the nonsaturated magnetization at the high-field region. The ferromagnetic phase is evident from the observed S-shaped hysteresis loops with well-defined coercive fields at the low-field region.…”

“…Figure shows the RT magnetization loops of a Zn 1– x Mn x O representative film with x = 0.07 before and after postannealing at 600 °C for 4 h in a vacuum and in air. In these curves, we removed the PARA contribution and presented only the ferromagnetic contribution to the magnetization for better clarity. ,, Similar annealing effects were systematically observed in all other Mn-doped films, while the undoped ZnO film showed a diamagnetic behavior, regardless of postannealing treatment. Compared to the as-deposited film, the film annealed in a vacuum showed stronger FM.…”

“…The M S values at room temperature were initially estimated from the ferromagnetic contribution to the total magnetization curves presented in Figure a . For example, the M S value for the doped film with x = 0.03 is found to be about 0.1 emu/cm 3 .…”