I need to know what substitution site for Co2+ in ZnO is good for magnetism in Cobalt doped ZnO thin films. Also, please suggest how to get that preferred site occupation for Co2+ in ZnO?
ZnO can be crystallized into two crystal phases, namely : hexagonal (wurtzite, C6V-symmetry) and cubic (zinc blende, Td-symmetry). In both cases, the Zn and oxide are tetragonal. Cobalt relate to the transition elements with unfilled 3d-electron shell. He have such electron configuration s2d7. Zinc did not relate to the transition elements since its have fulled 3d-electron shell. Its electron configuration is s2d10. However, both Zn and Co are two positive charged in ZnO (Zn2+). Thus, Co2+ replace Zn2+. Such replacement is very favorable since the ionic radii both elements are same (0.74 A).
ZnO can be crystallized into two crystal phases, namely : hexagonal (wurtzite, C6V-symmetry) and cubic (zinc blende, Td-symmetry). In both cases, the Zn and oxide are tetragonal. Cobalt relate to the transition elements with unfilled 3d-electron shell. He have such electron configuration s2d7. Zinc did not relate to the transition elements since its have fulled 3d-electron shell. Its electron configuration is s2d10. However, both Zn and Co are two positive charged in ZnO (Zn2+). Thus, Co2+ replace Zn2+. Such replacement is very favorable since the ionic radii both elements are same (0.74 A).
The existence of FM in Co-doped ZnO is controversial. See Phys. Rev. Lett. 100(2008)157201 and Phys. Rev. B 81(2010)214414
The origins of the FM (if it is observed at all) is higly controversial, too.
*Appl. Phys. Lett. 84, 1338 (2004); doi: 10.1063/1.1650915
*New Journal of Physics 10 (2008) 065002 (21pp)
*Advances in CondensedMatter Physics Volume 2012, Article ID 363981, 5 pages, doi:10.1155/2012/363981
The existence of ferromagnetism in ZnO:Co system has been theoretically predicted in [K. SATO and H. KATAYAMA-YOSHIDA, Jpn. J. Appl.Phys. 40 (2001) L334]. This attributed to the double exchange interaction or the RKKY interaction between Co ions. First report about the room temperature ferromagnetic features have been presented in [K. UEDA, H. TABATA and T. KAWAI, Appl. Phys. Lett.79 (2001) 988. ]. However, in this case it is shown that the ferromagnetic metal behavior occurs. It indicates, that the observed ferromagnetism may be originated from Co ferromagnetic precipitates. Currently, there are a lot works devoted to the study of ZnO:Co system. I think, that it would be correct to say that the mechanism of ferromagnetism in ZnO:Co, predicted theoretically, convincingly did not confirmed experimantally yet.
Yuriy Gnatenko given Nice explanation, ZnO can be crystallized into two crystal phases, (1) Hexagonal and (2) cubic.
In both cases, the Zn and oxide are tetragonal. Cobalt relate to the transition elements with unfilled 3d-electron shell. He have such electron configuration s2d7. Zinc did not relate to the transition elements since its have fulled 3d-electron shell. Its electron configuration is s2d10. However, both Zn and Co are two positive charged in ZnO (Zn2+). Thus, Co2+ replace Zn2+. Such replacement is very favorable since the ionic radii both elements are same (0.74 A).
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