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arXiv 2103.03182cond-mat.str-el
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近藤合金相干击穿的光发射特征:动力学平均场论方法

Photo-emission signatures of coherence breakdown in Kondo alloys: dynamical mean-field theory approach

Bishal Poudel, Claudine Lacroix, Gertrud Zwicknagl, Sébastien Burdin

摘要:

本文采用动态平均场论(DMFT)和静态平均场近似,研究了正方晶格上的近藤合金模型。我们计算和分析了光电特性作为电子填充$n_c$,近藤杂质浓度$x$,近藤温度$T_K$的强度的函数。我们提供了一个完整的描述的角度分辨光电子能谱(ARPES)的顺磁近藤阶段预期的信号。通过对费米面的分析,我们观察到了先前预测的强$T_K$在$x=n_c$的类Lifshitz跃迁,并讨论了色散从稠密相干态到稀近藤态的演化.在较小的$T_K$,我们发现,这种转变标志着在$x=n_c$的连贯性的崩溃成为一个交叉。然而,我们发现另一个过渡在一个较小的浓度$x^\star$的有效质量连续消失。$x^\star$分离的一个分支和两个分支的ARPES分散体分别表征稀释和密集近藤顺磁制度。还描述了$x-T_K$相图,表明在$x^\star$的转变可能是实验观察到的,因为磁有序相稳定在低得多的$T_K$。反铁磁相和铁磁相的费米面重建也进行了讨论。

英文摘要:

We study the Kondo alloy model on a square lattice using dynamical mean-field theory (DMFT) for Kondo substitution and disorder effects, together with static mean-field approximations. We computed and analyzed photoemission properties as a function of electronic filling $n_c$, Kondo impurity concentration $x$, and strength of Kondo temperature $T_K$. We provide a complete description of the Angle Resolved Photoemission Spectroscopy (ARPES) signals expected in the paramagnetic Kondo phases. By analyzing the Fermi surface, we observe the Lifshitz-like transition predicted previously for strong $T_K$ at $x=n_c$ and we discuss the evolution of the dispersion from the dense coherent to the dilute Kondo regimes. At smaller $T_K$, we find that this transition marking the breakdown of coherence at $x=n_c$ becomes a crossover. However, we identify another transition at a smaller concentration $x^\star$ where the effective mass continuously vanishes. $x^\star$ separates the one-branch and the two-branches ARPES dispersions characterizing respectively dilute and dense Kondo paramagnetic regimes. The $x-T_K$ phase diagrams are also described, suggesting that the transition at $x^\star$ might be experimentally observable since magnetically ordered phases are stabilized at much lower $T_K$. Fermi surface reconstructions in antiferromagnetic and ferromagnetic phases are also discussed.

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