Vacancy defects in epitaxial La0.7Sr0.3MnO3 thin films on LaAlO3 substrates were detected by using a variable-energy positron beam. The line-shape S parameter of the epitaxial thin films deposited at different O pressures was measured as a function of the implanting positron energy. The results showed that the S-parameter of the films changed non-monotonically with deposition O pressure. For films deposited at lower O pressures, the increase in S-value in the films was attributed to the increase in O vacancies and/or related defect–VO complexes. For those deposited at higher O pressures, the larger S-parameter of the films was caused by grain boundaries and/or metallic ion vacancies.

Vacancy Defects in Epitaxial La0.7Sr0.3MnO3 Thin Films Probed by a Slow Positron Beam. S.W.Jin, X.Y.Zhou, W.B.Wu, C.F.Zhu, H.M.Weng, H.Y.Wang, X.F.Zhang, B.J.Ye, R.D.Han: Journal of Physics D, 2004, 37[13], 1841-4