Ferromagnetic resonance signature of metallic Co clusters in ferromagnetic ZnCoO thin films

H. J. Von Bardeleben (1) , N. Jedrecy (1) , Jean-Louis Cantin (1)

1 INSP - Institut des Nanosciences de Paris

Highly Co-doped Zn(0.7)Co(0.3)O thin films that can be reproducibly grown ferromagnetic by pulsed laser deposition have been investigated by optical absorption and ferromagnetic resonance spectroscopy (FMR). The saturation magnetization depends strongly on the O(2) content during the growth, the highest value being obtained for the lowest oxygen pressure conditions. Whereas the optical absorption spectra confirm the incorporation of Co as Co(Zn)(2+) in ZnO, the FMR spectra prove the additional presence of randomly oriented metallic Co nanoparticles. The angular variation in the FMR spectra allows us to determine in the most ferromagnetic film the effective magnetization, 4 pi M similar to 800 G at 300 K and the g factor, g=2.18, which is that of metallic Co. The fraction of the two species Co(Zn)(2+) and Co metal is estimated to be similar to 3:1 (C) 2008 American Institute of Physics.

Domaines: Matière Condensée [cond-mat]

H. J. Von Bardeleben, N. Jedrecy, Jean-Louis Cantin. Ferromagnetic resonance signature of metallic Co clusters in ferromagnetic ZnCoO thin films. Applied Physics Letters, 2008, 93 (14), pp.142505. ⟨10.1063/1.2998309⟩. ⟨hal-01290156⟩