Orbital-selective coherence-incoherence crossover and metal-insulator transition in Cu-doped NaFeAs

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTIVITY;    STRONGLY CORRELATED SYSTEMS;    ELECTRONIC-STRUCTURE;    IRON PNICTIDES;    MOTT INSULATOR;    ORDER;    FRUSTRATION;    MAGNETISM;    DYNAMICS;    PROGRESS;   

DOI  :  10.1103/PhysRevB.103.155115

来源: SCIE

【 摘 要 】

We study the effects of electron-electron interactions and hole doping on the electronic structure of Cu-doped NaFeAs using the density functional theory plus dynamical mean-field theory (DFT+DMFT) method. In particular, we employ an effective multiorbital Hubbard model with a realistic band structure of NaFeAs in which Cu-doping was modeled within a rigid band approximation and compute the evolution of the spectral properties, orbital-selective electronic mass renormalizations, and magnetic properties of NaFeAs on doping with Cu. In addition, we perform fully charge self-consistent DFT+DMFT calculations for the long-range antiferromagnetically ordered Na(Fe,Cu)As with Cu x = 0.5 with a real-space ordering of Fe and Cu ions. Our results reveal a crucial importance of strong electron-electron correlations and local potential difference between the Cu and Fe ions for understanding the k-resolved spectra of Na(Fe,Cu)As. On Cu-doping, we observe a strong orbital-selective localization of the Fe 3d states accompanied by a large renormalization of the Fe xy and xz/yz orbitals. Na(Fe,Cu)As exhibits bad-metal behavior associated with a coherence-to-incoherence crossover of the Fe 3d electronic states and local moments formation near a Mott metal-insulator transition (MIT). For heavily doped NaFeAs with Cu x similar to 0.5 we obtain a Mott insulator with a band gap of similar to 0.3 eV which is characterized by divergence of the quasiparticle effective mass of the Fe xy states. In contrast to this, the quasiparticle weights of the Fe xz/yz and e states remain finite at the MIT. The MIT occurs via an orbital-selective Mott phase to appear at Cu x similar or equal to 0.375 with the Fe xy states being Mott localized. We propose the possible importance of Fe/Cu disorder to explain the magnetic properties of Cu-doped NaFeAs.

【 授权许可】

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