Surface and interface properties of La2/3Sr1/3MnO3 thin films on SrTiO3 (001)

Lina Chen, Zhen Wang, Gaomin Wang, Hangwen Guo, Mohammad Saghayezhian, Zhaoliang Liao, Yimei Zhu, E. W. Plummer, and Jiandi Zhang
Phys. Rev. Materials 3, 044407 – Published 22 April 2019

Abstract

Understanding and manipulating properties emerging at a surface or an interface require a thorough knowledge of structure-property relationships. We report a study of a prototype oxide system, La2/3Sr1/3MnO3 grown on SrTiO3(001), by combining in situ angle-resolved x-ray photoelectron spectroscopy, ex situ x-ray diffraction, and scanning transmission electron microscopy/spectroscopy with electric transport measurements. We find that La2/3Sr1/3MnO3 films thicker than 20 unit cells (u.c.) exhibit a universal behavior with no more than one u.c. intermixing at the interface but at least 3 u.c. of Sr segregation near the surface, which is (La/Sr)O terminated. The conductivity vs film thickness shows the existence of nonmetallic layers with thickness 6.5±0.9u.c., which is independent of film thickness but mainly relates to the deviation of Sr concentration near the surface region. Below 20 u.c., the surface of the films appears mixed, (La/Sr)O with MnO2 termination. Decreasing film thickness to less than 10 u.c. leads to the enhanced deviation of chemical composition in the films and eventually drives the film insulating. Our observation offers a natural explanation for the thickness-driven metal-nonmetal transition in thin films based on the variation of film stoichiometry.

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  • Received 9 June 2018
  • Revised 25 January 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.3.044407

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Lina Chen1,*, Zhen Wang1,2, Gaomin Wang1, Hangwen Guo1,†, Mohammad Saghayezhian1, Zhaoliang Liao1,‡, Yimei Zhu2, E. W. Plummer1, and Jiandi Zhang1

  • 1Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
  • 2Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

  • *Present address: School of Physics, Nanjing University, Nanjing, P. R. China.
  • Present address: School of Physics, Fudan University, Shanghai, P. R. China.
  • Present address: University of Science and Technology of China Hefei, Anhui 230029, P. R. China.

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Issue

Vol. 3, Iss. 4 — April 2019

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