Andris Šutka, Tanel Käämbre, Urmas Joost, Kuno Kooser, Mati Kook, Roberto Felix Duarte, Vambola Kisand, Mikhael Maiorov, Nicola Döbelin, Krisjanis Smits
Here we are reporting solvothermal synthesis derived diluted magnetic and plasmonic Co-Ga co-doped ZnOnanocrystals with high magnetization values (from 1.02 to 4.88 emu/g) at room temperature. Co-Ga co-doped ZnO nanocrystals show up to 2 fold increase in saturation magnetization compared to Co doped ZnO nanocrystals at the same Co concentration, with the observed room temperature magnetization higher than previously reported values for multifunctional magnetic and plasmonic nanocrystals, and the effect of Ga suggesting some role of the correspondingly introduced itinerant charge. While at the lowest Ga content the nanoparticles appear homogeneously doped, we note that already a moderate Ga content of several percent triggers a fraction of Co to segregate in metallic form in the bulk of the nanoparticles. However, the amount of segregated Co is not sufficient to account for the total effect, whereas a dominating contribution to the observed magnetism has to be related to itinerant charge mediated exchange interactions.
Published in Journal of Alloys and Compounds