Observation of Negative Magnetic Hysteresis Loop in ZnO Thin Films

Abstract

We report on the observation of an unusual negative magnetic hysteresis loop in ZnO thin film codoped with cobalt and aluminum (Co-Al:ZnO), while other transition-metal-doped ZnO films, such as Cu-doped ZnO and Mn-doped ZnO, exhibit normal hysteresis loops. The unusual magnetic behavior is ascribed to the presence of double magnetic layers with different magnetic moments due to the change of structural defects across the film layers. Positron annihilation measurements confirmed the presence of unique microstructural changes in the Co-Al:ZnO film. This study shows that defects in diluted magnetic semiconductors may induce not only ferromagnetism but also novel magnetic behaviors.

Synthesis, characterization, photophysical, and magnetic studies of mixed‐ligand thorium(IV) complex of 2‐hydroxy‐5‐sulfobenzoic acid and 1,10‐phenanthroline

“…[63] The substances exhibiting SRMHs have typical diamagnetic features. However, they figure like ferromagnetic loops as observed in many synthesized materials like Fe 2 O 3 Co-Al:ZnO [64] and CoFeAlO. [56] In the synthesized complex, the loop was observed at the middle (À4000 to +4000 Oe) of the field strength while rest was the straight line indicating overall the diamagnetic behavior as expected for the thorium metal with 5f 0 configuration.…”