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Indexed by:期刊论文

Date of Publication:2017-01-01

Journal:SOLID STATE COMMUNICATIONS

Included Journals:SCIE、EI、Scopus

Volume:250

Page Number:123-128

ISSN No.:0038-1098

Key Words:ZnCoO; Magnetism; Absorption spectrum; First-principles calculations

Abstract:Co-doped ZnO was studied using first-principles methods with comparison to experimental results taken from epitaxial Zn1-xCoxO(x similar to 0.05) films. Density of Co2+ ions was determined using absorption spectra for the first time, and then a definite correlation between metallic Co clusters and the magnetism of the ZnCoO films was proved and the average number of Co atoms in the metallic Co clusters was estimated to be less than 200 using a superparamagnetic model. First-principles calculations of ZnCoO alloys and the relevant problems were discussed by comparing the electronic structures with absorption spectra and the results calculated by Tanabe-Sugano theory. U correction was proved to be necessary for calculating the band-gap energy of ZnCoO alloys, but other optical properties related to Co2+ ions are incorrect and the conclusion for magnetic properties is ambiguous due to uncertainty of the calculated highly localized states, which are in pressing for solution in study of material properties relevant to electronic structure.