Local electronic structure of Mn dopants in ZnO probed by resonant inelastic x-ray scattering

The electronic structure of Mn dopants in ZnO epitaxial thin films synthesized at different temperatures has been investigated using resonant inelastic x-ray scattering. The resulting Mn L 2,3 x-ray emission spectra of Zn 0.8 Mn 0.2 O (resonantly excited at L 2 and L 3 absorption edges) reveal different spectral features depending on the growth temperature of the films. The relative integral intensity ratio of Mn L 2 to Mn L 3 emission lines is greatly suppressed in the case of nonmagnetic Zn 0.8 Mn 0.2 O grown at 700 °C due to L 2 L 3 M 4,5 Coster–Kronig transitions. The ferromagnetic sample grown at 600 °C exhibits a normal oxide structure. The results suggest that a high growth temperature causes direct Mn–Mn bonds from the segregation of Mn atoms in ZnO. Therefore the disappearance of ferromagnetism in Mn-doped ZnO can be attributed to antiferromagnetic Mn–Mn exchange interactions due to the inhomogeneous local environment around the Mn impurities.