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The effects of oxygen in spinel oxide Li1+xTi2-xO4-δ thin films.

Yanli JiaGe HeWei HuHua YangZhenzhong YangHeshan YuQinghua ZhangJinan ShiZefeng LinJie YuanBeiyi ZhuLin GuHong LiKui Jin
Published in: Scientific reports (2018)
The evolution from superconducting LiTi2O4-δ to insulating Li4Ti5O12 thin films has been studied by precisely tuning the oxygen pressure in the sample fabrication process. In superconducting LiTi2O4-δ films, with the increase of oxygen pressure, the oxygen vacancies are filled gradually and the c-axis lattice constant decreases. When the oxygen pressure increases to a certain critical value, the c-axis lattice constant becomes stable, which implies that the sample has been completely converted to Li4Ti5O12 phase. The two processes can be manifested by the angular bright-field images of the scanning transmission electron microscopy techniques. The transition temperature (T ch ) of magnetoresistance from the positive to the negative shows a nonmonotonic behavior, i.e. first decrease and then increase, with the increase of oxygen pressure. We suggest that the decrease Tch can be attributed to the suppressing of orbital-related state, and the inhomogeneous phase separated regions contribute positive MR and thereby lead to the reverse relation between Tch and oxygen pressure.
Keyphrases
  • electron microscopy
  • magnetic resonance
  • room temperature
  • deep learning
  • machine learning
  • computed tomography
  • optical coherence tomography
  • mass spectrometry