Analysis on the energetics, magnetism and electronic properties in a 45° ZnO grain boundary doped with Gd
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
Materials Science and Engineering Program
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AbstractThe structural stability and magnetic properties of a grain boundary (GB) formed by aligning two ZnO single crystals oriented at an angle of 45° is investigated by density functional theory, using generalized gradient approximation (GGA) and taking the U parameter into consideration for the 4f impurity states. We found that the GB is stable with no dangling bonds and inter-granular structures. The stability of defects such as Gd substituted to the Zn site (Gd), Zn vacancy (V) and O vacancy (V) as well as defect complexes Gd-Gd, Gd-V, and Gd-V are analyzed using formation energy calculations. It is found that Gd-Gd clusters prefers to form at the GB. The spin polarization at the Gd sites is too localized and the exchange coupling energy is insufficient to overcome the thermal fluctuations. However, we show that the presence of V increases the hybridization between p orbitals of O as well as d orbitals of Zn, which can assist in increasing the magnetic polarization of the system. This work advances the understanding of the ferromagnetism in Gd-doped ZnO, indicating that Gd clustering at the GB is not likely to contribute to the ferromagnetism.
CitationSasikala Devi AA, Roqan IS (2018) Analysis on the energetics, magnetism and electronic properties in a 45° ZnO grain boundary doped with Gd. RSC Advances 8: 13850–13856. Available: http://dx.doi.org/10.1039/c8ra00985f.
SponsorsWe acknowledge the financial support from General Directorate of Research Grants (AT-34-450) from King Abdul-Aziz City of Science and Technology (KACST), Kingdom of Saudi Arabia.
PublisherRoyal Society of Chemistry (RSC)