Eur. Phys. J. B 35, 481-491 (2003)
https://doi.org/10.1140/epjb/e2003-00301-6

Effects of vacuum annealing on the transport property of La_0.67Sr _0.33MnO_3-δ films

¹ State Key Laboratory for Magnetism, Institute of Physics and Center for Condensed Matter Physics, The Chinese Academy of Sciences, Beijing 100080, P.R. China
² Department of Physics, The Chinese University of Hong Kong, Hong Kong, P.R. China

Corresponding author: ^a jrsun@g203.iphy.ac.cn

Received: 11 April 2003
Revised: 8 August 2003
Published online: 24 October 2003

Abstract

Effects of oxygen content on the transport behavior of epitaxial La_2/3Sr _1/3MnO films on (110) NdGaO₃ and (001) SrTiO₃ substrates have been experimentally studied. A quantitative relation between the temperature of metal-to-insulator transition (T_p) and the content of oxygen vacancies is established, and it is found that oxygen non-stoichiometry causes a monotonic decrease of T_p. A comparison to crystals LaSr_xMnO₃ indicates that the reduction of hole concentration due to the incorporation of anionic vacancies dominates the variation of T_p, while the vacancies themselves influence the detailed features of the T_p- dependence. Strain in the film affects the effects of oxygen deficiency, and the metal-to-insulator transition disappears at a smaller value in tensily stressed films. In the temperature region above T_p, oxygen vacancies affect the resistive behavior of the films mainly by modulating the content of Mn⁴⁺. In contrast, extra effects due to the scattering of oxygen vacancies become important at low temperatures, causing an exponential increase of resistivity with . A further analysis indicates that oxygen deficiency enhances magnetic scattering, and leads to a resistivity upturn of the form when is significant.