We theoretically study the effect of electron-electron interactions on the metallic state of quasicrystals. To address the problem, we introduce the extended Hubbard model on the Ammann-Beenker tiling as a simple theoretical model. The model is numerically solved within an inhomogeneous mean-field theory. Because of the lack of periodicity, the metallic state is nonuniform in the electron density even in the noninteracting limit. We clarify how this charge distribution pattern changes with electron-electron interactions. We find that the intersite interactions change the distribution substantially and in an electron-hole asymmetric way. We clarify the origin of these changes through the analyses in the real and perpendicular spaces. Our results offer a fundamental basis to understand the electronic states in quasicrystalline metals.
Origin of Quantum Criticality in Yb-Al-Au Approximant Crystal and Quasicrystal
为了深入了解准晶体Yb $_{15}$ Al $_{34}$ Au $_{51}$中出现非常规量子临界的机制，对准晶体Yb $_{14}$ Al $_{35}$ Au $_{51}$进行了理论分析.通过建立近似晶体的极小模型，发现由于Yb原子上4f电子的强关联，在费米能级附近出现了重准粒子带.我们发现，在蔡型团簇中，第三壳层Yb的4f电子和第四壳层Al的3 p电子之间的电荷转移模式得到了显著的增强，并且动量依赖性几乎是平坦的。模式耦合理论表明，磁化率和价磁化率在零场极限下表现出$χ\sim T^{-0.5}$，并且即使在近似晶体中，当通过改变参数来满足某些条件时，也可以表示为四十年内温度与磁场之比$T/B$的单一标度函数，例如，通过施加压力。的关键起源是澄清是由于强的局域性的临界Yb-价涨落和小布里渊区反映大的单位电池，从而引起的极小的特征能量尺度。这也给出了一个自然的解释量子临界在准晶对应的无限的单位晶胞尺寸的限制。
Effects of Crystalline Electronic Field and Onsite Interorbital Interaction in Yb-based Quasicrystal and Approximant Crystal
为了深入了解最近在准晶体Yb $_{15}$ Al $_{34}$ Au $_{51}$和近似晶体（AC）Yb $_{14}$ Al $_{35}$ Au $_{51}$中发现的一种新的量子临界现象，我们讨论了在AC中Yb处的晶体电场（CEF）的性质，并表明由于Al/Au混合位的存在，在每个Yb位上会出现不均匀的CEF能级.然后通过在Yb的4f和5d轨道之间引入库仑排斥，构造了AC上电子态的极小模型。基态的数值计算表明，Yb价态的晶格常数依赖性很好地解释了最近通过在准晶和AC中Al和Au元素的系统替代所做的测量，其中准晶Yb $_{15}$ Al $_{34}$ Au $_{51}$正好位于Yb价态开始剧烈变化的点处。我们的计算令人信服地表明，这确实是证据，该材料是位于量子临界点的Yb-价跃迁。
Soft and hard x-ray orbital-resolved photoemission study of a strongly correlated Cd-Ce quasicrystal approximant
Julius-Maximilians-Universität Würzburg（维尔茨堡大学）；The University of Osaka（大阪大学）；RIKEN SPring-8 Center（理化学研究所SPring-8中心）；Institute for Open and Transdisciplinary Research Initiatives, The University of Osaka（大阪大学开放与跨学科研究倡议研究院）
Derivation of a non-stoichiometric 1/1 quasicrystal approximant from a stoichiometric 2/1 quasicrystal approximant and maximization of magnetocaloric effect
Emergence of long-range magnetic order from spin-glass state by tuning electron density in a stoichiometric Ga-based quasicrystal approximant
Department of Material Science and Technology, Tokyo University of Science（东京科学大学物质科学与技术系）；Research Institute of Science and Technology, Tokyo University of Science（东京科学大学理工学研究科）；Cryogenic Research Center, The University of Tokyo（东京大学低温研究中心）
