Superdislocations and point defects in pyrochlore Yb2Ti2O7 single crystals and implication on magnetic ground states

This study reports atomic-scale characterization of structural defects in Yb 2 Ti 2 O 7, a pyrochlore oxide whose subtle magnetic interactions is prone to small perturbations. Due to discrepancies in the reported magnetic ground states, it has become a pressing issue to determine the nature of defec...

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Bibliographic Details
Published in:Scientific reports 2018-11, Vol.8 (1), p.1-10, Article 17202
Main Authors: Shafieizadeh, Zahra, Xin, Yan, Koohpayeh, Seyed M., Huang, Qing, Zhou, Haidong
Format: Article
Language:English
Subjects:
639/301/119
639/301/119/997
charge transport
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Crystals
defects
Disease transmission
Humanities and Social Sciences
magnetism and spin physics
materials and chemistry by design
multidisciplinary
optics
Oxides
Point defects
quantum information science
Science
Science (multidisciplinary)
Single crystals
superconductivity
synthesis (novel materials)
thermal conductivity
Transmission electron microscopy
Vectors
Ytterbium
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Summary:This study reports atomic-scale characterization of structural defects in Yb 2 Ti 2 O 7, a pyrochlore oxide whose subtle magnetic interactions is prone to small perturbations. Due to discrepancies in the reported magnetic ground states, it has become a pressing issue to determine the nature of defects in this system. In the present study, we use atomic resolution scanning transmission electron microscopy techniques to identify the type of defects in the ytterbium titanate single crystals grown by the conventional optical floating zone (FZ) method. In addition to the known point defects of substitution Yb on Ti B-sites, extended defects such as dissociated superdislocations and anti-phase boundaries were discovered for the first time in this material. Such defects were prevalently observed in the FZ grown single crystals (of a darker color), in contrast to the stoichiometric white polycrystalline powders or high quality colorless single crystals grown by the traveling solvent floating zone technique. The lattice strains from these extended defects result in distortions of Yb-tetrahedron. A change of Ti valance was not detected at the defects. Our findings provide new insights into understanding the nature of defects that are of great importance for the physical property studies of geometrically frustrated compounds. Furthermore, this work sheds light on the complicated core structure of superdislocations that have large Burgers vectors in oxides with complex unit cells.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-35283-w