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首页> 外文期刊>Journal of Experimental and Theoretical Physics >Doping Dependence of Correlation Effects in K_(1–x)Fe_(2–y)Se_2 Superconductors: LDA' + DMFT Investigation1
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Doping Dependence of Correlation Effects in K_(1–x)Fe_(2–y)Se_2 Superconductors: LDA' + DMFT Investigation1

机译：K_（1-x）Fe_（2-y）Se_2超导体中相关效应的掺杂依赖性：LDA'+ DMFT研究1

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摘要

We present a detailed LDA' + DMFT investigation of the doping dependence of correlation effects in the novel K_(1–x)Fe_(2–y)Se_2 superconductor. Calculations are performed at four different hole doping levels, starting from a hypothetical stoichiometric composition with the total number of electrons equal to 29 per unit cell through 28 and 27.2 electrons toward the case of 26.52, which corresponds to the chemical composition K_(0.76)Fe_(1.72)Se_2 studied in recent ARPES experiments. In the general case, the increase in hole doping leads to quasiparticle bands in a wide energy window ±2 eV around the Fermi level becoming more broadened by lifetime effects, while correlation-induced compression of Fe-3d LDA' bandwidths stays almost the same, of the order of 1.3 for all hole concentrations. However, close to the Fermi level, the situation is more complicated. In the energy interval from –1.0 eV to 0.4 eV, the bare Fe-3d LDA' bands are compressed by significantly larger renormalization factors up to 5 with increased hole doping, while the value of Coulomb interaction remains the same. This fact manifests the increase in correlation effects with hole doping in the K_(1–x)Fe_(2–y)Se_2 system. Moreover, in contrast to typical pnictides, K_(1–x)Fe_(2-y)Se_2 does not have well-defined quasiparticle bands on the Fermi levels, but has a “pseudogap”-like dark region instead. We also find that with the growth of hole doping, Fe-3d orbitals of various symmetries are affected by correlations differently in different parts of the Brillouin zone. To illustrate this, we determine the quasiparticle mass renormalization factors and energy shifts that transform the bare Fe-3d LDA' bands of various symmetries into LDA' + DMFT quasiparticle bands. These renormalization factors effectively mimic more complicated energy-dependent self-energy effects and can be used to analyze the available ARPES data.
机译：我们对新型K_（1-x）Fe_（2-y）Se_2超导体中相关效应的掺杂依赖性进行了详细的LDA'+ DMFT研究。计算是在四个不同的空穴掺杂水平上进行的，从假设的化学计量组成开始，即每单位电池的电子总数等于29，通过28和27.2电子，直至26.52，对应于化学成分K_（0.76）Fe_ （1.72）Se_2在最近的ARPES实验中进行了研究。在一般情况下，空穴掺杂的增加会导致费米能级附近±2 eV的宽能量窗中的准粒子带由于寿命效应而变得更宽，而相关诱导的Fe-3d LDA'带宽的压缩几乎保持不变，对于所有空穴浓度，约为1.3。但是，情况接近费米水平，情况更加复杂。在从–1.0 eV到0.4 eV的能量区间中，裸露的Fe-3d LDA'带被明显更大的重归一化因子压缩，最多增加5，空穴掺杂增加，而库仑相互作用的值保持不变。这一事实表明，在K_（1–x）Fe_（2–y）Se_2系统中，与空穴掺杂相关的效应有所增加。此外，与典型的杀虫剂相比，K_（1-x）Fe_（2-y）Se_2在费米能级上没有明确定义的准粒子带，而是具有类似“伪狗粮”的暗区。我们还发现，随着空穴掺杂的增长，在布里渊区的不同部分，各种对称的Fe-3d轨道受到相关性的不同影响。为了说明这一点，我们确定了准粒子质量重新归一化因子和能量转移，这些能量转移将各种对称的裸Fe-3d LDA'带转变为LDA'+ DMFT准粒子带。这些重归一化因子有效地模拟了更复杂的依赖于能量的自能量效应，可用于分析可用的ARPES数据。

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