计算了镱化合物的光电导[ $σ(ω)$ ]谱（YbAl $_3$，YbAl $_2$，YbCu $_2$ Si $_2$，YbNi $_2$ Ge $_2$，YbInCu $_4$，YbRh $_2$ Si $_2$，YbIr $_2$ Si $_2$，和YbB $_{12}$）的直接带间跃迁，主带计算，并与实验获得的$σ(ω)$光谱的结果进行了比较。实验$σ(ω)$光谱中的中红外峰（中红外峰）和远红外肩结构（远红外肩）的光谱特征可以用一个公共重整化因子的能带计算来描述。这一结果表明，Yb化合物的红外光谱起源于Yb $4f$态的带间跃迁，但Yb $4f$态移动到费米能级，具有强电子相关性。
英文摘要：
We have calculated optical conductivity [$σ(ω)$] spectra of ytterbium compounds (YbAl$_3$, YbAl$_2$, YbCu$_2$Si$_2$, YbNi$_2$Ge$_2$, YbInCu$_4$, YbRh$_2$Si$_2$, YbIr$_2$Si$_2$, and YbB$_{12}$) based on the direct interband transition derived from first-principle band calculation and compared the results with the experimentally obtained $σ(ω)$ spectra. The spectral feature of a peak in the middle-infrared region (mid-IR peak) and a shoulder structure in the far-infrared region (far-IR shoulder) in the experimental $σ(ω)$ spectra can be described by the band calculation with a common renormalization factor. This result indicates that the infrared spectra of Yb compounds originate from the interband transition from the Yb $4f$ state but that the Yb $4f$ state shifts to the Fermi level with strong electron correlation.
We consider the structure of anisotropic exchange interactions in ytterbium-based insulating rare-earth magnets built from edge-sharing octahedra. We argue the features of trivalent ytterbium and this structural configuration allow for a qualitative determination of the different anisotropic exchange regimes that may manifest in such compounds. The validity of such super-exchange calculations is tested through comparison to the well-characterized breathing pyrochlore compound Ba$_3$Yb$_2$Zn$_5$O$_{11}$. With this in hand, we then consider application to three-dimensional pyrochlore spinels as …
The ground ytterbium doublet in h-YbMnO3 and the related low-temperature peculiarities of the compound
Institute of Spectroscopy, Russian Academy of Sciences（俄罗斯科学院光谱研究所）；Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences（中国科学院合肥物质科学研究院固体物理研究所材料物理重点实验室）
While most of the rare earth metals readily form trihydrides, due to increased stability of the filled 4f electronic shell for Yb(II), only YbH$_{2.67}$, formally corresponding to Yb$^{\rm II}$(Yb$^{\rm III}$H$_4$)$_2$ or Yb$_3$H$_8$, remains the highest hydride of ytterbium. Utilizing diamond anvil cell methodology and synchrotron powder x-ray diffraction we have attempted to push this limit further via hydrogenation of metallic Yb (at room temperature and heated in situ) and of Yb$_3$H$_8$. Compression of the latter has also been investigated in a neutral pressure transmitting medium, PTM. W…
We present results on resistivity ($ρ$), magnetization ($M$), thermal conductivity ($κ$), magnetostriction ($\frac{ΔL}{L(0)}$) and specific heat ($C_{p}$) of charge-orbital ordered antiferromagnetic Nd$_{0.8}$Na$_{0.2}$MnO$_{3}$ compound. Magnetic field-induced antiferromagnetic/charge-orbital ordered insulating to ferromagnetic metallic transition leads to giant magnetothermal conductivity and magnetostriction effect. The low-temperature irreversibility behavior in $ρ$, $M$, $κ$ and $\frac{ΔL}{L(0)}$ due to field cycling together with striking similarity among the field and temperature depend…
Thermal Conductivity and Specific Heat of the Spin-Ice Compound Dy$_2$Ti$_2$O$_7$: Experimental Evidence for Monopole Heat Transport
自旋冰化合物Dy $_2$ Ti $_2$ O $_7$中的基元激发可以描述为在由磁性Dy离子形成的烧绿石晶格内独立传播的磁单极子。我们研究了B的热导率κ（B）与磁场的关系||[001]并观察到源自磁激发的磁热传输的明显证据。磁贡献κ mag与磁场有很强的相关性，并与磁化强度M（B）有关。由κ mag与磁比热之比得到的扩散系数在低于1K时大大增强，表明自旋冰态的自旋激发具有高的迁移率.
Thermal conductivity (κ) of a distorted spin diamond-chain system, Cu_3(CO_3)_2(OH)_2, is studied at low temperatures down to 0.3 K and in magnetic fields up to 14 T. In zero field, the κ(T) curve with heat current along the chain direction has very small magnitudes and shows a pronounced three-peak structure. The magnetic fields along and perpendicular to the chains change the κstrongly in a way having good correspondence to the changes of magnetic specific heat in fields. The data analysis based on the Debye model for phononic thermal conductivity indicates that the heat transport is due to …
The electronic properties of Cerium (Ce) and ytterbium (Yb) intermetallic compounds may display a more local or more itinerant character depending on the interplay of the exchange interactions among the $4f$ electrons and the Kondo coupling between $4f$ and conduction electrons. For the more itinerant case, the materials form heavy-fermions once the Kondo effect is developed at low temperatures. Hence, a temperature variation occurs in the electronic structure that can be traced by investigating the optical conductivity ($σ(ω)$) spectra. Remarkably, the temperature variation in the $σ(ω)$ spec…
Observing the anisotropic optical response of the heavy-fermion compound UNi2Al3
重费米子的光学电导率可以揭示这些强关联电子系统中载流子动力学的基本性质。在这里，我们通过测量太赫兹辐射的透射率和相移，通过一个薄膜的UNi 2Al 3，具有六方晶体结构的材料，重费米子上的红外光学的传统技术。我们推导出的光学电导率在以前无法访问的频率范围内，此外，我们解决的光学响应的各向异性（平行和垂直于六边形平面）。在7 cm ^-1附近的频率下，我们发现了一种强烈的温度依赖性和各向异性的光学电导率，令人惊讶的是，它大致遵循直流行为。
Kagomé-staircase compound Ni$_3$V$_2$O$_8$ is an attractive multiferroic material exhibiting rich phase diagrams. However, the magnetic properties and magnetic transitions have been studied only above 1.3 K. In this work, we study the thermal conductivity ($κ$) of Ni$_3$V$_2$O$_8$ single crystals at low temperatures down to 0.3 K and in magnetic fields up to 14 T. In zero field, the magnetic transitions from the low-temperature incommensurate (LTI) phase to the commensurate phase (C) and then to a second commensurate phase (C') yield anomalies in $κ(T)$ curves at $T\rm_{LC}$ = 3.7 K and $T\rm_…
Model of the electron-phonon interaction and optical conductivity of Ba$_{1-x}$K$_x$BiO$_3$ superconductors
我们研究了Ba $_{1-x}$ K $_x$ Bi O $_3$化合物的物理性质，重点研究了其光学性质。从简单的Holstein模型，描述了一个单一的频带耦合到氧气呼吸模式与参数来自第一性原理计算的结果，是在很好的协议与广泛的实验信息。它占$x=0$ %的绝缘母体化合物，具有直接（光学）和间接间隙，以及$x = 0.38$周围的金属绝缘体过渡。强的电子-声子耦合导致谱重重新分配的频率尺度远大于特征声子频率和强烈的非谐声子。我们发现，在相界附近的金属相是接近的极化区。
In this paper we report comprehensive experimental and theoretical investigation of magnetic and electronic properties of the intermetallic compounds Pr2Fe17 and Gd2Fe17. For the first time electronic structure of these two systems was probed by optical measurements in the spectral range of 0.22-15 micrometers. On top of that charge carriers parameters (plasma frequency and relaxation frequency) and optical conductivity s(w) were determined. Self-consistent spin-resolved bandstructure calculations within the conventional LSDA+U method were performed. Theoretical interpetation of the experiment…
Spinon localization in the heat transport of the spin-1/2 ladder compound (C$_5$H$_{12}$N)$_2$CuBr$_4$
本文报道了自旋为1/2的梯形体系（C $_5$ H $_{12}$ N）$_2$ CuBr $_4$中磁场依赖的热输运性质.的热导率$κ(B)$是只有微弱的影响，由场诱导之间的无间隙的Luttinger液体状态实现的$B_{c1}< B < B_{c2}$和有间隙的状态，这表明没有一个直接的贡献的自旋激发的热传输。然而，我们观察到的热导率强烈抑制的磁场深处的Luttinger液体状态。这些令人惊讶的观察进行了讨论，在有限的阶梯段和自旋声子umklapp散射的主要声子热输运的自旋子的本地化。
The low-temperature transport properties (resistivity, thermal conductivity, thermoelectric power) are experimentally investigated for the compound YbMn2Sb2. Large Seebeck coefficient and nearly linear temperature dependence of resistivity are obtained. The thermal conductivity is large and has mainly phonon origin. Appreciable anomalies of transport characteristics near the antiferromagnetic transition point are found. Possible influence of pseudo-Kondo scattering is discussed.
Domain-wall excitons and optical conductivity in one-dimensional Wigner lattices
最近发现掺杂的共边Cu-O链化合物如Na $_3$ Cu $_2$ O $_4$和Na $_8$ Cu $_5$ O $_{10}$是一维Wigner晶体的实现，我们研究了这类系统的光谱。一维维格纳晶体中的电荷激发用分数电荷畴壁激发来描述。我们调查的解析和数值计算的畴壁激发占主导地位的光吸收，并分析的色散和参数范围的激子状态的特性的长程库仑吸引畴壁之间。在这里，我们专注于魏格纳晶格在四分之一填充相关的钠$_3$铜$_2$ O $_4$和分析，特别是第二邻居跳$t_2$，这是重要的边缘共享链化合物的作用。大的$t_2$通过软畴壁激子驱动维格纳晶格的不稳定性朝向具有不同于维格纳晶格的调制周期的电荷密度波。此外，我们计算的直流电导率的温度依赖性，并表明，它可以描述的激活行为结合$T^{-α}$依赖的迁移率。
Pyrochlore iridates have recently attracted growing interest in condensed matter physics because of their potential for realizing new topological states. In order to achieve such quantum states, it is essential to understand themagnetic properties of these compounds, as their electronic structures are strongly coupled with theirmagnetic ground states. In this work, we report a systematic study of the magnetic properties of pyrochlore Y2Ir2O7 and its hole-doped compounds by performing magnetic, electron spin resonance, electrical transport, and x-ray photoelectron spectroscopy (XPS) measurement…
Calculation of Optical Conductivity, Resistivity and Thermopower of Filled Skutterudite CeRu$_4$Sb$_{12}$ based on a Realistic Tight-binding Model with Strong Correlation
ZrSiS is a nodal-line semimetal, whose electronic band structure contains a diamond-shaped line of Dirac nodes. We carried out a comparative study on the optical conductivity of ZrSiS and related compounds ZrSiSe, ZrSiTe, ZrGeS, and ZrGeTe by reflectivity measurements over a broad frequency range combined with density functional theory calculations. The optical conductivity exhibits a distinct U shape, ending at a sharp peak at around 10000~cm$^{-1}$ for all studied compounds, except for ZrSiTe. The U shape of the optical conductivity is due to transitions between the linearly dispersing bands…
The new family of unconventional iron-based superconductors discovered in 2006 immediately relieved their copper-based high-temperature predecessors as the most actively studied superconducting compounds in the world. The experimental and theoretical effort made in order to unravel the mechanism of superconductivity in these materials has been overwhelming. Although our understanding of their microscopic properties has been improving steadily, the pairing mechanism giving rise to superconducting transition temperatures up to 55 K remains elusive. And yet the hope is strong that these materials…
Co-based shandite Co$_3$Sn$_2$S$_2$ is a representative example of magnetic Weyl semimetals showing rich transport phenomena. We thoroughly investigate magnetic and transport properties of hole-doped shandites Co$_3$In$_x$Sn$_{2-x}$S$_2$ by first-principles calculations. The calculations reproduce nonlinear reduction of anomalous Hall conductivity with doping In for Co$_3$Sn$_2$S$_2$, as reported in experiments, against the linearly decreased ferromagnetic moment within virtual crystal approximation. We show that a drastic change in the band parity character of Fermi surfaces, attributed to th…
We report electrical and thermal transport properties of polycrystalline ZrTe3. The polycrystalline sample shows semiconducting behavior in contrast to the established semi-metallic character of the compound. However the charge density wave (CDW) transition remains intact and its clear signatures are observed in thermal conductivity and Seebeck coefficient, in the wide temperature range 50 - 100 K. The thermal conductivity points to additional scattering from the low frequency phonons (phonon softening) in the vicinity of CDW transition. The transport in the polycrystalline compounds is govern…
We report on the epitaxial growth, structural and electrical properties of metallic pyrochlore bismuth ruthenate heterostructures grown along both the [001] and [111] directions. Ordered pyrochlore thin films were obtained with highly oriented texture along the [001] and [111] crystallographic directions. Density functional theory calculations of the electronic band structure and density of states indicated that Bi$_2$Ru$_2$O$_7$ is semimetallic and that hybridization of the Ru 4$d$ and Bi 6$p$ orbitals via the anion network at the Fermi energy was responsible for the metallicity. Electrical c…
We performed optical studies on CaFeAsF single crystals, a parent compound of the 1111-type iron-based superconductors that undergoes a structural phase transition from tetragonal to orthorhombic at $T_s$ = 121 K and a magnetic one to a spin density wave (SDW) state at $T_N$ = 110 K. In the low temperature optical conductivity spectrum, after the subtraction of a narrow Drude peak, we observe a pronounced singularity around 300 cm$^{-1}$ that separates two regions of quasilinear conductivity. We outline that these characteristic absorption features are signatures of Dirac fermions, similar to …
Historically, the genesis of anomalous Hall effect (AHE) in magnetic materials has always been a fascinating yet controversial topic in the solid state physics community. Recent progress on the understanding of this topic has revealed an intimate connection between the Berry curvature of occupied electronic states and the intrinsic AHE. Magnetic Weyl semimetals with broken time reversal symmetry is a classic example, which is expected to show large contributions to Berry curvature around the topological nodes and hence to the AHE. Here, we report a kagome metallic ferromagnet Nd$_3$Al, with a …
We show that the temperature dependence of conductivity of high mobility organic crystals Pentacene and Rubrene can be quantitatively described in the framework of the model where carriers are scattered by quenched local impurities and interact with phonons by Su-Schrieffer-Hegger (SSH) coupling. Within this model, we present approximation free results for mobility and optical conductivity obtained by world line Monte Carlo, which we generalize to the case of coupling both to phonons and impurities. We find fingerprints of carrier dynamics in these compounds which differ from conventional meta…
Superconductivity in PdTe2 heavy transition metal based compounds is rapidly developing field in condensed matter physics community. Here, we report superconductivity in a nominal ternary telluride Ta2Pd0.97Te6 compound, which is synthesized in sealed evacuated quartz ampoule. The resultant compound is crystallized in layered monoclinic Ta4Pd3Te16 phase with space group C2/m, having lattice parameters a=21.304(6)A, b=3.7365(7)A, and c=17.7330A with Beta =120.65(1)degree. Both transport and magnetic measurements demonstrated bulk superconductivity at 4.4K in studied polycrystalline sample. The …
