Spatial distribution and electronic state of Co in epitaxial anatase CoxTi1−xO2 thin films grown by reactive sputtering

Abstract

The magnetic and phase properties of Co x Ti 1Ϫx O 2 anatase thin films grown epitaxially on ͑001͒ LaAlO 3 by a reactive rf magnetron cosputter deposition have been examined. Co x Ti 1Ϫx O 2 (x ϭ0.07) thin films exhibit room-temperature ferromagnetism, as evidenced by hysteresis in M-H loop. Chemical mapping indicates segregation of the Co dopant atoms in these films. However, x-ray photoelectron spectroscopy suggests that the segregated Co is not metallic, but in the Co ϩ2 state. These results are consistent with a segregated Ti-CoO phase being responsible for the ferromagnetic behavior.

Study of hydrogenation versus de-loading of Co and Mn doped ZnO semiconductor

“…8). The 2p peak positions and their satellite structures confirm high spin divalent Co [18][19][20]. The spectra deny the presence of Co metallic state, since in that case the Co 2p 3/2 peak would have appeared at [21].…”

Magnetic anisotropy in nanocrystalline Co-doped ZnO thin films

“…Few researchers claim that the ferromagnetism in Zn 1Àx Co x O is due to intrinsic effect [13][14][15], while others describe it as an extrinsic effect due to the secondary phases of cobalt oxides and Co metallic clusters [16][17][18][19]. Besides, Khare et al [20] demonstrated that zinc interstitials defects are critical to ferromagnetism rather than oxygen vacancies in Co-doped ZnO.…”

Investigation of Mn-doped Si films prepared by magnetron cosputtering

“…It can be found that Mn and Si peaks are uniformly distributed across the film surface. If there are Mn clusters, we would expect an enhancement in Mn signal intensity in the precipitates [14]. However, this is not observed.…”