Carrier localization in perovskite nickelates from oxygen vacancies, M. Kotiuga, Z. Zhang, J. Li, F. Rodolakis, H. Zhou, R. Sutarto, F. He, Q. Wang, Y. Sun, Y. Wang, N. A. Aghamiri, S. B. Hancock, L. P. Rokhinson, D. P. Landau, Y. Abate, J. W. Freeland, R. Comin, S. Ramanathan and K. M. Rabe, Proceedings of the National Academy of Sciences of the USA, 116, 21992 (2019)