Room-temperature ferromagnetism in hydrogenated bulk samples of Zn0.98Mn0.02O, synthesized by standard solid-state reaction, was studied. The effect of hydrogenation time upon the structural and magnetic properties of the samples was explored. Magnetic measurements showed that the samples synthesized by sintering in air at ~800C exhibited paramagnetic behavior and the same samples, upon annealing in a gaseous mixture of Ar (90%) and H (10%) at ~800C, became ferromagnetic at room temperature. Based upon the structural and magnetic properties of the samples, it was argued that room temperature ferromagnetism in the hydrogenated samples originated from the O vacancies and some defects at Zn sites.

Oxygen Vacancies Induced Room Temperature Ferromagnetism in Hydrogenated Mn-Doped ZnO. Sharma, V.K., Varma, G.D.: Journal of Applied Physics, 2007, 102[5], 056105