Uniaxial Strain-Controlled Ground States in Manganite Films

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Abstract
Strongly correlated perovskite oxides exhibit a plethera of intriguing phenomena and stimulate a great potential for multifunctional device applications. Utilizing tunable uniaxial strain, rather than biaxial or anisotropic strain delivered from the crystallography of a single crystal substrate, to modify the ground state of strongly correlated perovskite oxides has rarely been addressed for phase-space control. Here, we show that the physical properties of La2/3Ca1/3MnO3 (LCMO) films are remarkably different depending on the crystallographic orientations of the orthorhombic NdGaO3 (NGO) substrates. And more importantly, the antiferromagnetic charge-ordered insulating (COI) phase induced in the (100) or (001)-oriented LCMO films can be dramatically promoted (or suppressed) by a uniaxial tensile (or compressive) bending stress along the in-plane [010] direction. By contrast, the COI phase is nearly unaffected along the other transverse in-plane directions. Results from scanning transmission electron microscopy reveal that the (100) or (001)-oriented LCMO films are uniaxially tensile strained along the [010] direction, while the LCMO/NGO(010) and LCMO/NGO(110) films remaining a bulk-like ferromagnetic metallic state exhibit a different strain state. Density functional theory calculations further reveal that the cooperatively increased Q2 Jahn-Teller distortion and charge ordering may be indispensible for the inducing and promoting of the COI phase. These findings provide a path to understand the correlation between local and extended structural distortions imparted by coherent epitaxy and their electronic states for quantum phase engineering.
Funding Information
  • Ministry of Science and Technology of the People's Republic of China (2016YFA0401003, 2017YFA0403502)
  • China Postdoctoral Science Foundation (2018M632557)
  • U.S. Department of Energy (DE-SC0012375)
  • National Natural Science Foundation of China (11804342, 11974326, 51872278)
  • Chinese Academy of Sciences
  • Anhui Provincial Key Laboratory for Condensed Matter Physics at Extreme Conditions
  • Hefei Science Center of Chinese Academy of Sciences (2018ZYFX002)

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