Zhang Guoren, Pavarini Eva
School of Sciences, Nantong University, Nantong, 226019, People's Republic of China.
Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
Phys Rev Lett. 2023 Jul 21;131(3):036504. doi: 10.1103/PhysRevLett.131.036504.
The low-energy j_{eff}=1/2 band of Sr_{2}IrO_{4} bears stark resemblances with the x^{2}-y^{2} band of La_{2}CuO_{4}, and yet no superconductivity has been found so far by doping Sr_{2}IrO_{4}. Behind such a behavior could be inherent failures of the j_{eff}=1/2 picture, in particular when electrons or holes are introduced in the IrO_{2} planes. In view of this, here we reanalyze the j_{eff}=1/2 scenario. By using the local-density approximation plus dynamical mean-field theory approach, we show that the form of the effective j_{eff}=1/2 state is surprisingly stable upon doping. This supports the j_{eff}=1/2 picture. We show that, nevertheless, Sr_{2}IrO_{4} remains in essence a multiorbital system: The hybridization with the j_{eff}=3/2 orbitals sizably reduces the Mott gap by enhancing orbital degeneracy, and part of the holes go into the j_{eff}=3/2 channels. These effects cannot be reproduced by a simple effective screened Coulomb repulsion. In the optical conductivity spectra, multiorbital processes involving the j_{eff}=3/2 states contribute both to the Drude peak and to relatively low-energy features.
Sr₂IrO₄的低能jₑբ=1/2能带与La₂CuO₄的x² - y²能带极为相似，然而迄今为止通过对Sr₂IrO₄进行掺杂尚未发现超导性。这种现象背后可能是jₑբ=1/2模型存在内在缺陷，特别是当电子或空穴被引入IrO₂平面时。鉴于此，我们在此重新分析jₑբ=1/2的情况。通过使用局域密度近似加动力学平均场理论方法，我们表明有效jₑբ=1/2态的形式在掺杂时惊人地稳定。这支持了jₑբ=1/2模型。不过，我们表明Sr₂IrO₄本质上仍是一个多轨道系统：与jₑբ=3/2轨道的杂化通过增强轨道简并性大幅降低了莫特能隙，并且部分空穴进入了jₑբ=3/2通道。这些效应无法通过简单的有效屏蔽库仑排斥来重现。在光导率谱中，涉及jₑբ=3/2态的多轨道过程对德鲁德峰和相对低能特征都有贡献。
