The magnetic properties of pure transition-like metals are discussed within the single site approximation, to take into account the electron correlation. The metal is described by two hybridized bands one of which includes the Coulomb correlation. Our results indicate that ferromagnetism follows from adequate values of the correlation and hybridization.
Magnetism in two-dimensional (2D) van der Waals (vdW) materials has lately attracted considerable attention from the point of view of both fundamental science and device applications. Obviously, establishing the detailed and solid understanding of their magnetism is the key first step toward various applications. Although $\mathrm{Fe_3GeTe_2}$ is a representative ferromagnetic (FM) metal in this family, many aspects of its magnetic and electronic behaviors still remain elusive. Here, we report our new finding that $\mathrm{Fe_3GeTe_2}$ is a special type of correlated metal known as 'Hund metal…
Muon spin rotation technique is used to study magnetic ordering in ultra-pure samples of SrCu$_{1-x}$Ni$_x$O$_2$, an archetypical $S=1/2$ antiferromagnetic Heisenberg chain system with a small amount of $S=1$ defects. The ordered state in the parent compound is shown to be highly homogeneous, contrary to previous report [M. Matsuda et al., Phys. Rev. B \textbf{55}, R11953 (1997)]. Even minute amount of Ni impurities result in inhomogeneous order and a decrease of the transition temperature. At as little as $0.5$~\% Ni concentration, magnetic ordering is entirely suppressed. The results are com…
A recently synthesised series of isostructural compounds Ba$_4$NbTM$_3$O$_{12}$ (TM = Mn, Rh and Ir) with transition-metal trimers in a face-sharing geometry makes it possible to examine a tendency to the molecular orbitals (MO) formation going from $3d$ to $5d$ transition metal ions. Our $ab$ $initio$ calculations of electronic and magnetic properties describe the experimental findings and demonstrate gradual transition from the picture of localized electrons for Mn to the MO picture for Rh and especially for Ir. We also show that the often used criterion, according to which the metal-metal d…
The pyrochlore iridate In$_2$Ir$_2$O$_7$ is a strong $J_{\mathrm{eff}} = 1/2$ Mott insulator with frustrated magnetism. Despite the large trigonal crystal field, a small admixture of $J_{\mathrm{eff}} = 3/2$ component in the $J_{\mathrm{eff}} = 1/2$ bands and a small splitting of $J_{\mathrm{eff}} = 3/2$ bands are observed as compared with other pyrochlore iridates A$_2$Ir$_2$O$_7$ (A: trivalent cation). We argue that the reduced inter-site hopping between the $J_{\mathrm{eff}} = 1/2$ and the $J_{\mathrm{eff}} = 3/2$ manifold plays a predominant role in the distinct behavior of In$_2$Ir$_2$O$_…
Band-Saddle-Point Engineering in Mixed $A$-site $A$V$_3$Sb$_5$ Kagome Metals
Physikalisches Institut, Universität Stuttgart（斯图加特大学第一物理研究所）；Felix Bloch Institute for Solid-State Physics, Leipzig University（莱比锡大学费利克斯·布洛赫固体物理研究所）；Materials Department, University of California Santa Barbara（加州大学圣塔芭芭拉分校材料系）；Materials Science and Technology Division, Oak Ridge National Laboratory（橡树岭国家实验室材料科学与技术部）；Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research（德累斯顿罗森多夫亥姆霍兹中心离子束物理与材料研究所）
Properties of iron oxides at the extreme conditions are of essential importance in condensed matter physics and Geophysics. The recent discovery of a new type of iron oxide, Fe4O5, at high pressure and high temperature of Earth's deep interior attracts great interests. In this paper, we report the electronic structure and the magnetic properties of Fe4O5 predicted by the density functional theory plus dynamic mean field theory (DFT+DMFT) approach. We find that Fe4O5 stays metallic from ambient pressure to high pressure. The magnetic moments of iron atoms at the three different crystallographic…
Site-polarized Mott phases competing with a correlated metal in twisted WSe$_2$
University of Hamburg（汉堡大学）；The Hamburg Centre for Ultrafast Imaging（汉堡超快成像中心）；University of Würzburg（维尔茨堡大学）；Max Planck Institute for the Structure and Dynamics of Matter（物质结构与动力学马普研究所）；RWTH Aachen University（亚琛工业大学）；Center for Computational Quantum Physics, Flatiron Institute（平顿研究所计算量子物理中心）；Tsientang Institute for Advanced Study, Zhejiang（浙江大学前沿技术研究院（紫江））；Songshan Lake Materials Laboratory（松山湖材料实验室）
We synthesized a new high-entropy-alloy-type (HEA-type) superconductor (Fe,Co,Ni,Cu,Ga)Zr2 with a Tc of 2.9 K. The EDX analyses revealed that the actual composition of the transition-metal site (Tr-site) is Tr = Fe0.18Co0.18Ni0.16Cu0.25Ga0.23, which gives the configurational entropy of mixing ΔSmix = 1.60R for the Tr site. Neutron powder diffraction revealed that the sample has a tetragonal CuAl2-type (space group: #140). The lattice constant of a monotonically decreases with decreasing temperature, but the lattice constant of c does not exhibit a clear shrinkage. Isotropic displacement parame…
We provide experimental and theoretical evidence for a novel type of pressure-induced insulator-metal transition characterized by site-selective delocalization of the electrons. Mössbauer spectroscopy, X-ray diffraction and electrical transport measurements on Fe$_2$O$_3$ to 100 GPa, along with dynamical mean-field theory (DFT+DMFT) calculations, reveal this site-selective Mott transition between 50 and 68 GPa, such that the metallization can be described by ($^\rm{VI}$Fe$^{3+\rm{HS}}$)$_2$O$_3$ [$R\bar{3}c$ structure] $\overrightarrow{\tiny\rm{50~GPa}}$ ($^\rm{VIII}$Fe$^{3+\rm{HS~VI}}$Fe$^\rm…
RV6Sn6 (R=rare earth) compounds are appealing materials platforms for exploring the interplay between R-site magnetism and nontrivial band topology associated with the nonmagnetic vanadium-based kagome network. Here we present the synthesis and characterization of the kagome metal TbV6Sn6 via single-crystal x-ray diffraction, magnetization, transport, and heat capacity measurements. Magnetization measurements reveal strong, uniaxial magnetic anisotropy rooted in the alignment of Tb3Å moments in the interplane direction below 4.3(2) K. TbV6Sn6 exhibits multiband transport behavior with high mob…
Site-Selective Mott Transition in a Quasi-One-Dimensional Vanadate V6O13
利用轨道分辨51 V核磁共振谱研究了准一维体系V6 O 13的金属-绝缘体转变的微观机制。我们发现，过渡涉及一个网站选择性d轨道的顺序提升两个VO 6链中的一个的双重轨道简并。另一个链在整个过渡中在单占据的dxy轨道上留下顺磁矩。这两条链分别稳定了基态的轨道辅助自旋Peierls态和反铁磁长程序。择位Mott跃迁可能是反常金属和Mott-Peierls对偶性的一个来源。
We compare the trends on the strength of electronic correlations across the different phases of elemental Pu focusing on its site and orbital dependence, using a combination of density functional theory (DFT) and dynamical mean field theory (DMFT) calculations within the vertex corrected one crossing approximation. We find that Pu-5$f$ states are more correlated in $δ$-Pu, followed by some crystallographic sites in $α$ and $β$ phases. In addition, we observe that Pu-5$f_{5/2}$ and Pu-5$f_{7/2}$ orbital differentiation is a general feature of this material, as is site differentiation in the low…
We investigate the effect of charge self-consistency (CSC) in density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations compared to simpler "one-shot" calculations for materials where interaction effects lead to a strong redistribution of electronic charges between different orbitals or between different sites. We focus on two systems close to a metal-insulator transition, for which the importance of CSC is currently not well understood. Specifically, we analyze the strain-related orbital polarization in the correlated metal CaVO$_3$ and the spontaneous electronic char…
The nexus between negative charge-transfer and reduced on-site Coulomb energy in a correlated topological metal CoTe$_2$
National Synchrotron Radiation Research Center（国家同步辐射研究中心）；Experimentelle Physik VII, Universität Würzburg（维尔茨堡大学第七物理研究所）；RIKEN SPring-8 Center（理化学研究所SPring-8中心）；Program on Key Materials, Academy of Innovative Semiconductor and Sustainable Manufacturing (AISSM), National Cheng Kung University（国立成功大学创新半导体与永续制造学院关键材料计划）；Department of Physics, National Cheng Kung University（国立成功大学物理学系）；Taiwan Consortium of Emergent Crystalline Materials, National Science and Technology Council（国家科学及技术委员会台湾新兴结晶材料联盟）；The University of Tokyo（东京大学）
We construct a family of translationally invariant lattice models with a large number ($N$) of orbitals at every site coupled together via single electron tunneling. By tuning the relative strength of the electronic bandwidth and on-site interactions, that have a modified Sachdev-Ye-Kitaev (SYK) form, we demonstrate a number of unusual features at strong coupling and in the large$-N$ limit. We find examples of (i) an intrinsic non-BCS superconducting instability arising out of an incoherent non-Fermi liquid metal, and, (ii) an instability of an incipient heavy Fermi liquid metal to superconduc…
