Contradictory nature of Co doping in ferroelectric BaTi O3

Patrick Ponath, Andrew O'Hara, Hai Xia Cao, Agham B. Posadas, Rama Vasudevan, M. Baris Okatan, S. Jesse, Morgann Berg, Zongyao Li, Desai Zhang, Andrew J. Kellock, Alex De Lozanne, Jianshi Zhou, Sergei Kalinin, David J. Smith, Alexander A. Demkov

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12 Scopus citations

Abstract

The growth of Co-substituted BaTiO3 (BTO) films on Ge(001) substrates by molecular beam epitaxy is demonstrated. Energy-dispersive x-ray spectroscopy and transmission electron microscopy images confirm the uniform Co distribution. However, no evidence of magnetic ordering is observed in samples grown for Co concentrations between 2% and 40%. Piezoresponse force microscopy measurements show that a 5% Co-substituted BTO sample exhibits ferroelectric behavior. First-principles calculations indicate that while Co atoms couple ferromagnetically in the absence of oxygen vacancies, the occurrence of oxygen vacancies leads to locally antiferromagnetically coupled complexes with relatively strong spin coupling. The presence of a significant amount of oxygen vacancies is suggested by x-ray photoelectron spectroscopy measurements.

Original languageEnglish
Article number205121
JournalPhysical Review B
Volume94
Issue number20
DOIs
StatePublished - 2016

Funding

This work was supported by the Air Force Office of Scientific Research under Grant No. FA9550-12-10494 and the Texas Advanced Computing Center. H.X.C. thanks the National Natural Science Foundation of China for supporting her stay at the University of Texas at Austin under Grant No. 11104194. A portion of this research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE (R.K.V., S.V.K.). Research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, with support from M.B.O. and S.J.

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