Room temperature ferromagnetism in undoped and Mn doped CdO nanostructures

• Simple synthesis method is used to synthesize Cd1−xMnxO nanostructures.
• The optical band gap of Cd1−xMnxO nanostructures is calculated.
• Cd1−xMnxO (x=0) nanostructure shows weak RTFM.
• The RTFM of Cd1−xMnxO (x=0) is explained by a model based on electronic distribution.
• The RTFM nature of Cd1−xMnxO is increased consistently from x=0.01 to 0.05.

Cd1−xMnxO (x=00–0.07) nanostructures were synthesized and their structural, optical and magnetic properties were investigated. The shift of diffraction peaks towards lower angle side with increase of Mn content indicates the incorporation of Mn2+ ions into the CdO lattice. The values of optical band gaps were calculated at each value of Mn concentration. The values of band gap were increased by increasing the Mn concentrations as a direct consequence of the quantum confinement effect. The undoped CdO [Cd1−xMnxO (x=0.00)] nanostructure shows weak ferromagnetic nature at room temperature. The ferromagnetic nature increases consistently with increase of Mn concentrations from x=0.01 to 0.05 and then slightly drops for x=0.07. As there were no magnetic impurities present in the samples, we assume that the origin of ferromagnetism in the undoped CdO nanostructures could be due to formation of CdO structure in triplet state (S=1). However, the consistent increase of magnetic nature with Mn doped (x=0.01–0.05) CdO nanostructures might be attributed to the ferromagnetic coupling between the spins and enhancement of spin concentrations due to entering of Mn atom into the lattice. The sudden drop of ferromagnetic nature at x=0.07 may be due to the presence of anti-ferromagnetic coupling.

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