Thickness dependent Mn valence in La$_{\mathrm{0.7}}$Sr$_{\mathrm{0.3}}$MnO$_{\mathrm{3}}$ thin films

ORAL

Abstract

The Mn valence in thin film La$_{\mathrm{0.7}}$Sr$_{\mathrm{0.3}}$MnO$_{\mathrm{3}}$ is studied as a function of film thickness in the range of 1-16u.c. Using a combination of bulk and surface sensitive x-ray absorption spectroscopy techniques, the layer-by-layer Mn valence is determined for these film thicknesses. It is found that while the bulk averaged valence hovers around its expected value of 3.3, a significant deviation occurs within several unit cells of the surface and interface, where the surface and interface valence are determined to be 4 and 2.68, respectively. These results are supported by theoretical calculations. The change in valence from the expected bulk value arises from the polar discontinuity at the film-substrate interface.

*NSF (DMR-1608656), U.S. Department of Energy DE-SC0016176, US Department of Energy DE-AC02-05CH, National Natural Science Foundation of China (No. 11274060)

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Authors

  • Robbyn Trappen

    • Department of Physics and Astronomy, West Virginia University, WV 26506, USA

  • Vu Thanh Tra

    • Institute of Physics, National Chiao Tung University, 30010 HsinChu, Taiwan

  • Chih-Yeh Huang

    • Department of Physics and Astronomy, West Virginia University, WV 26506, USA

  • Jinling Zhou

    • Department of Physics and Astronomy, West Virginia University, WV 26506, USA

  • Guerau Cabrera

    • Department of Physics and Astronomy, West Virginia University, WV 26506, USA

  • Ying-Hao Chu

    • Institute of Physics, National Chiao Tung University, 30010 HsinChu, Taiwan

  • Shuai Dong

    • Department of Physics, Southeast University, Nanjing 211189, China

  • Mikel Holcomb

    • Department of Physics and Astronomy, West Virginia University, WV 26506, USA