Two-phase structure of ultra-thin La–Sr–MnO films

• Published in: Thin solid films 2006-10, Vol.515 (2), p.691-694
• Main Authors: Balevičius, S., Cimmperman, P., Petrauskas, V., Stankevič, V., Tornau, E.E., Žurauskienė, N., Abrutis, A., Plaušinaitienė, V., Sawicki, M., Dietl, T., Aleszkiewicz, M.
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electrical properties of specific thin films; Electrical resistivity; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Magnetization; Manganite thin films; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.12.240

The structural, electrical and magnetic properties of ultra-thin La 0.83Sr 0.17MnO 3 (LSMO) films, deposited on NdGaO 3 substrate by using the MOCVD technique, were studied. The film thickness d varied in the range from 4 to 140 nm. X-ray and RHEED measurements demonstrated that the films had a two-phase structure. One phase had an orthorhombic face centred structure ( a = 0.406 nm and c = 0.46 nm), while the other one had a cubic perovskite-like structure with a = 0.388 nm. Low field dc resistance and magnetization vs. temperature dependences were investigated in the temperature range from 5 to 300 K using a conventional four-probe method and a SQUID magnetometer. It was found that the temperature of the resistivity maximum, T m, increases with increasing film thickness and that the value of the Curie temperature T C estimated from the temperature dependence of magnetization is very close to T m. Modelling of the remanent magnetization vs. temperature dependence based on a two-phase model was in agreement with experimental results. This model also explains the T m shift to lower temperatures with decreasing film thickness.