Abstract A recent study has demonstrated the cutting-edge techniques in applying large strains to the transition metal perovskite oxides up to 8%. In order to explore the unknown magnetic phase diagrams and physical properties of the perovskite SrIrO3, we employ first principles density-functional theory calculations to study the magnetic, electronic and dynamical properties of tetragonal SrIrO3 under epitaxial strains. There are four abrupt changes in the magnetic moment of Ir atom with in-plane epitaxial strain changing from -10% to +7% (positive/negative value corresponds to the tensile/compressive strain) relative to the cubic phase. In particular, under an in-plane compressive strain of ∼1.5% or tensile strain of ∼1%, a weak ferromagnetic to strong ferromagnetic transition is induced, whereas for a compressive strain lager than 7.7% or a tensile strain larger than 4.7%, the magnetic moment of Ir drops gradually with the increase of the strain. These magnetic transitions can be qualitatively explained by the Stoner model. In addition, the phonon instabilities of tetragonal SrIrO3 under both compressive and tensile strains are revealed by lattice dynamics calculations. These phonon instabilities of tetragonal SrIrO3 show potential polar metal behaviors which are similar to those found in tetragonal SrRuO3. This may stimulate further investigation in the properties of SrIrO3-based complex oxide interfaces.

中文翻译：

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外延应变下四方 SrIrO3 中异常的磁跃迁和声子不稳定性

摘要 最近的一项研究证明了将大应变应用于高达 8% 的过渡金属钙钛矿氧化物的尖端技术。为了探索钙钛矿 SrIrO3 未知的磁相图和物理性质，我们采用第一性原理密度泛函理论计算来研究外延应变下四方 SrIrO3 的磁、电子和动力学性质。相对于立方相，Ir 原子的磁矩有四个突变，面内外延应变从 -10% 变化到 +7%（正/负值对应于拉伸/压缩应变）。特别是，在约 1.5% 的面内压应变或约 1% 的拉伸应变下，会引起弱铁磁到强铁磁的转变，而对于大于 7 的压应变。7% 或拉伸应变大于 4.7%，Ir 的磁矩随着应变的增加而逐渐下降。Stoner 模型可以定性地解释这些磁跃迁。此外，通过晶格动力学计算揭示了在压缩应变和拉伸应变下四方 SrIrO3 的声子不稳定性。四方 SrIrO3 的这些声子不稳定性显示出与四方 SrRuO3 相似的潜在极性金属行为。这可能会刺激对基于 SrIrO3 的复合氧化物界面性质的进一步研究。通过晶格动力学计算揭示了四方 SrIrO3 在压缩应变和拉伸应变下的声子不稳定性。四方 SrIrO3 的这些声子不稳定性显示出潜在的极性金属行为，类似于在四方 SrRuO3 中发现的行为。这可能会刺激对基于 SrIrO3 的复合氧化物界面性质的进一步研究。通过晶格动力学计算揭示了四方 SrIrO3 在压缩应变和拉伸应变下的声子不稳定性。四方 SrIrO3 的这些声子不稳定性显示出潜在的极性金属行为，类似于在四方 SrRuO3 中发现的行为。这可能会刺激对基于 SrIrO3 的复合氧化物界面性质的进一步研究。