Defect engineering in perovskite oxides enables novel functionalities by inducing and controlling lattice defects, effectively breaking lattice symmetry, stabilizing polar states and inducing ferroelectricity in non-polar/paraelectric or ferro/antiferromagnetic oxide thin films. A polar state can be stabilized in SrMnO₃ (SMO) thin films by displacing Mn ions. However, conventional epitaxial strain engineering necessitates deposition on diverse single crystalline substrates with varying misfit strains and optimization of thin film growth conditions, posing challenges in achieving polar states in SMO thin films. In this study, polar distortion was achieved by inducing defects in SMO epitaxial thin films grown on Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ substrates La_0.7Sr_0.3MnO₃ (LSMO) electrode. Scanning transmission electron microscopy analysis revealed that Mn ion displacement and the c/a ratio increased on moving from the SMO/LSMO interface to the top surface of the SMO film. Electron energy loss spectroscopy depth profiles revealed variations in oxygen stoichiometry and Mn³⁺/Mn⁴⁺ ratio across the cross section of the SMO film. Consequently, a polar state was stabilized through strain gradient induced by defect chemistry in SMO thin films. Our study demonstrates that defect engineering can be effectively utilized in the realization of electric field-controlled magnetic devices at room temperature.

中文翻译：

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SrMnO3 薄膜中缺陷引起的极性畸变


钙钛矿氧化物中的缺陷工程通过诱导和控制晶格缺陷、有效打破晶格对称性、稳定极性状态并在非极性/顺电或铁/反铁磁性氧化物薄膜中诱导铁电性来实现新的功能。通过置换 Mn 离子，可以在 SrMnO₃ （SMO） 薄膜中稳定极性态。然而，传统的外延应变工程需要在具有不同 misfit 应变的不同单晶衬底上沉积，并优化薄膜生长条件，这对在 SMO 薄膜中实现极性状态提出了挑战。在本研究中，通过在 Pb（Mg_1/3Nb_2/3）O 3-PbTiO₃ 衬底 La_0.7Sr_0.3MnO₃ （LSMO） 电极上诱导生长的 SMO 外延薄膜缺陷来实现极性畸变。扫描透射电子显微镜分析显示，从 SMO/LSMO 界面移动到 SMO 膜顶面时，Mn 离子位移和 c/a 比值增加。电子能量损失光谱深度剖面揭示了 SMO 膜横截面上氧化学计量和 Mn³⁺/Mn⁴⁺ 比率的变化。因此，通过 SMO 薄膜中缺陷化学诱导的应变梯度稳定了极性状态。我们的研究表明，缺陷工程可以有效地用于在室温下实现电场控制的磁性器件。