Dynamics of the incorporation of Co into the wurtzite ZnO matrix and its magnetic properties

Preparation and structural-optical characterization of dip-coated nanostructured Co-doped ZnO dilute magnetic oxide thin films

“…The energy difference between the bands at 1.886 eV and 1.831 eV is 0.055 eV, which exactly corresponds to the energy of the vibrational mode E 2H (0.054 eV/ 437 cm À1 ), normally observed for both undoped and TM-doped ZnO wurtzite structure. 24,47,48 The difference in energy among the 1.886 eV, 1.872 eV and 1.857 eV bands, as well as the energy difference between the 1.831 eV and 1.815 eV bands, are 0.014 eV, 0.015 eV and 0.16 eV, respectively. These values, in turn, are in accordance with the energy for the vibrational mode E 2L (0.013 eV/105 cm À1 ).…”

“…22,[58][59][60] However, the V O state in the wurtzite ZnO is deep-donor state, 51,61 and, although deeper-donors states can hybridize to magnetic dopants, their smaller Bohr radii would require relatively higher dopant and defect concentrations to achieve a necessary spatial overlapping, and at such short-range antiferromagnetic superexchange interactions would be observed, instead of the desired ferromagnetic coupling. 48 Therefore, the most promising Table 3. The spectra are offset for clarity.…”

Defect induced room temperature ferromagnetism in high quality Co-doped ZnO bulk samples

“…Finally, we analyze the interaction between Co atoms into the w-ZnO lattice. Dealing with high quality (low level of defects) Co-doped w-ZnO samples we have already shown experimentally that the magnetic interaction between the Co atoms is AF [12,39], exceptionally with the concomitant introduction of structural defects into the w-ZnO lattice [61,63]. In previous theoretical calculations [24] we have also obtained AF coupling between two Co atoms in the w-ZnO lattice without defects, demonstrating the important role performed by structural defects in order to achieve the desired RTFM.…”

Local and electronic structure of Sr1-Gd TiO3 probed by X-ray absorption spectroscopy

“…6 shows that DOS for the Gd 4f states coincide with the position of the DOS for the Ti 3d(t2g) (between −11.0 and −9.0 eV) giving a contribution to the conduction band. Such hybridization, besides the structural distortion mentioned early, can explain why the conductivity and mainly the Seebeck coefficient is considerably affected by the Gd and, more generally, by the STO rare-earth doping [56,57].…”