Motivated by properties-controlling potential of the strain, we investigate strain dependence of structure, electronic, and magnetic properties of Sr₂IrO₄ using complementary theoretical tools: ab-initio calculations, analytical approaches (rigid octahedra picture, Slater-Koster integrals), and extended \(t-{{{\mathcal{J}}}}\) model. We find that strain affects both Ir-Ir distance and Ir-O-Ir angle, and the rigid octahedra picture is not relevant. Second, we find fundamentally different behavior for compressive and tensile strain. One remarkable feature is the formation of two subsets of bond- and orbital-dependent carriers, a compass-like model, under compression. This originates from the strain-induced renormalization of the Ir-O-Ir superexchange and O on-site energy. We also show that under compressive (tensile) strain, Fermi surface becomes highly dispersive (relatively flat). Already at a tensile strain of 1.5%, we observe spectral weight redistribution, with the low-energy band acquiring almost purely singlet character. These results can be directly compared with future experiments.

在应变的特性控制潜力的推动下，我们使用互补的理论工具研究 Sr ₂ IrO ₄的结构、电子和磁特性的应变依赖性：从头算计算、分析方法（刚性八面体图像、Slater-Koster 积分），和扩展\(t-{{{\mathcal{J}}}}\)模型。我们发现应变会影响 Ir-Ir 距离和 Ir-O-Ir 角，而刚性八面体图像不相关。其次，我们发现压缩应变和拉伸应变的行为根本不同。一个显着的特征是在压缩下形成了两个依赖键和轨道的载流子子集，一个类似指南针的模型。这源于应变诱导的 Ir-O-Ir 超交换和 O 现场能量的重整化。我们还表明，在压缩（拉伸）应变下，费米表面变得高度分散（相对平坦）。已经在 1.5% 的拉伸应变下，我们观察到光谱重量重新分布，低能带获得几乎纯单重态特征。这些结果可以直接与未来的实验进行比较。