MnO nanoparticles as the cause of ferromagnetism in bulk dilute Mn-doped ZnO

• Published in: Applied physics letters 2016-12, Vol.109 (25)
• Main Authors: Lançon, Diane, Nilsen, Gøran J., Wildes, Andrew R., Nemkovski, Kirill, Huang, Ping, Fejes, Dóra, Rønnow, Henrik M., Magrez, Arnaud
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4972956

We show that the observed ferromagnetic behavior of ZnO lightly doped with Mn coincides with the presence of MnO nanoparticles, whereas cluster-free Mn doped ZnO behaves paramagnetically. This conclusion is reached by a study of the structural and magnetic properties of powdered samples of (Mn x ,Zn1– x )O with x ≤ 0.033 using polarized neutron scattering. Two types of samples were synthesized via, respectively, a solid state method and the decomposition of hydrozincite. Further characterization has been performed using standard X-ray diffraction and magnetization measurements. The results show evidence for the formation of MnO nanoparticles in the highest doped samples for both synthesis methods, with a ferromagnetic behavior attributed to uncompensated Mn2+ in the MnO nanoparticles. The lower Mn-doped samples showed no evidence for structural segregation or magnetic correlations and showed only a paramagnetic behaviour.