Strain-induced crystal structure change in ultrathin films of Pr₀.₇Sr₀.₃MnO₃
Wang, Z. L. (Zhong Lin)
Wang, H. S.
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Ultrathin films (<30 nm) of Pr₀.₇Sr₀.₃MnO₃on LaAlO₃have been studied using transmission electron microscopy (TEM). It was shown that the films are highly uniform and defect-free, and that they are coherently strained to the smaller lattice parameter of the substrate, resulting in a tetragonal expansion perpendicular to the film plane and a change of crystal structure from the ordered orthorhombic of bulk materials to a simple tetragonal perovskite. The variation of the tetragonality with distance from the interface was also determined from high-resolution TEM images.