用高温溶液法生长了LaAu $_{2}$ In $_{4}$和CeAu $_{2}$ In $_{4}$单晶，并报道了CeAu $_{2}$ In $_{4}$的各向异性磁行为。该化合物以正交晶系结构结晶，空间群为\textit {Pnma}。LaAu $_{2}$ In $_{4}$表现出Pauli顺磁行为。CeAu $_{2}$ In $_{4}$在1.8 K以下不有序。CeAu $_{2}$ In $_{4}$的易磁化轴沿[010]方向。在晶体电场模型的基础上对磁化数据进行了分析。
英文摘要：
We have grown the single crystals of LaAu$_{2}$In$_{4}$ and CeAu$_{2}$In$_{4}$ by high temperature solution method and report on the anisotropic magnetic behavior of CeAu$_{2}$In$_{4}$ . The compounds crystallize in an orthorhombic structure with space group \textit {Pnma}. LaAu$_{2}$In$_{4}$ shows a Pauli-paramagnetic behavior. CeAu$_{2}$In$_{4}$ do not order down to 1.8 K. The easy axis of magnetization for CeAu$_{2}$In$_{4}$ is along [010] direction. The magnetization data is analyzed on the basis of crystalline electric field (CEF) model.
Magnetic field-tuned magnetic order and metamagnetic criticality in non-stoichiometric CeAuBi$_2$
University of Maryland（马里兰大学）；Missouri University of Science and Technology（密苏里科技大学）；Florida State University（佛罗里达州立大学）；National Institute of Standards and Technology（美国国家标准与技术研究院）；Canadian Institute for Advanced Research（加拿大高级研究院）
We investigate the temperature ($T$)-evolution of orbital anisotropy and its effect on spectral function and optical conductivity in Ce$_{2}$IrIn$_{8}$, using a first principles dynamical mean field theory combined with density functional theory. The orbital anisotropy develops by lowering $T$ and it is intensified below a temperature corresponding to the crystalline-electric field (CEF) splitting size. Interestingly, the depopulation of CEF excited states leaves a spectroscopic signature, "shoulder", in the $T$-dependent spectral function at the Fermi level. From the two-orbital Anderson impu…
We report temperature dependent magnetization and neutron diffraction measurements on the corundum related magnetoelectric antiferromagnet Mn$_{4}$Ta$_{2}$O$_{9}$. Measurements performed on a single crystalline specimen reveal that the magnetization is anisotropic, and a weak ferromagnetic component emerges well within the antiferromagnetically ordered state. Powder neutron diffraction measurements indicate that the magnetic structure comprises of antiferromagnetically coupled ferromagnetic chains of Mn$^{2+}$ spins aligned along the trigonal $c$ axis, in contrast to that reported in other iso…
Neutron scattering experiments have been performed to elucidate magnetic properties of the quasicrystal approximant Au$_{70}$Si$_{17}$Tb$_{13}$, consisting of icosahedral spin clusters in a body-centered-cubic lattice. Bulk magnetic measurements performed on the single crystalline sample unambiguously confirm long-range ordering at $T_{\rm C} = 11.6 \pm 1$ K. In contrast to the simple ferromagnetic response in the bulk measurements, single crystal neutron diffraction confirms a formation of intriguing non-collinear and non-coplanar magnetic order. The magnetic moment direction was found to be …
Crystalline anisotropy induces a second antiferromagnetic phase in the absence of SDW in the heavily hydrogen-doped LaFeAsO$_{1-x}$H$_x$ $(x\sim0.5 )$
采用密度泛函理论结合动力学平均场方法（DFT+DMFT）研究了重掺氢LaFeAsO $_{1-x}$ H $_x$ $(x\sim0.5 )$的电子和磁性.我们发现了氢原子和氧原子的条纹状有序结构，作为基态，具有与反铁磁（AF）顺序相同的配置。新的结构可以解释现有的实验结果有关的重H掺杂的LaFeAsO $_{1-x}$ H $_x$，如在平面内的电子各向异性和非均匀的磁性行为。在Fe- 3d $_{xz}$（xz）和Fe-3d $_{yz}$（yz）基态轨道之间观察到显著的各向异性，其中不存在由自旋密度波相产生的赝能隙，这被发现源于结晶各向异性。磁矩在空间上是不均匀的，并且对晶体构型很敏感。我们发现，非均匀的磁性行为与结构中的As-Fe-As键角有关。我们的研究结果将阐明铁基超导体中晶体细节和轨道自由度的重要性。
We have performed X-ray powder diffraction, magnetization, electrical resistivity, heat capacity and inelastic neutron scattering (INS) to investigate the physical properties of the intermetallic series of compounds CeCuBi$_{2-x}$Sb$_{x}$. These compounds crystallize in a tetragonal structure with space group $P4/nmm$ and present antiferromagnetic transition temperatures ranging from 3.6 K to 16 K. Remarkably, the magnetization easy axis changes along the series, which is closely related to the variations of the tetragonal crystalline electric field (CEF) parameters. This evolution was analyze…
CeRh$_6$Ge$_4$ is an unusual example of a stoichiometric heavy fermion ferromagnet, which can be cleanly tuned by hydrostatic pressure to a quantum critical point. In order to understand the origin of this anomalous behavior, we have characterized the magnetic ordering and crystalline electric field (CEF) scheme of this system. While magnetic Bragg peaks are not resolved in neutron powder diffraction, coherent oscillations are observed in zero-field $μ$SR below $T_{\rm C}$, which are consistent with in-plane ferromagnetic ordering consisting of reduced Ce moments. From analyzing the magnetic s…
本文采用密度泛函理论（DFT）+U方法对插层硫族化合物材料\ce{Fe_{0.25}TaS_2}的大磁晶各向异性进行了第一性原理研究。我们验证了单轴磁晶各向异性能（MAE）为15 meV/Fe。in the material材料.我们进一步分析了MAE对组成元素的依赖性以及自旋轨道耦合的影响。与传统的直觉相反，我们发现由于较重的元素Ta中的强自旋轨道耦合对MAE的贡献很小。结果表明，磁性离子的电子组态、晶场环境和相关效应是影响磁性离子稳定性的重要因素。
Transport and anisotropy in single-crystalline SrFe$_2$As$_2$ and $A_{0.6}$K$_{0.4}$Fe$_2$As$_2$ ($A$ = Sr, Ba) superconductors
我们用助熔剂法成功地生长了高质量的SrFe $_2$ As $_2$和A $_{0.6}$ K $_{0.4}$ Fe $_2$ As $_2$（A=Sr，Ba）单晶。测量了电阻率、比热容和霍尔系数。对于母体化合物SrFe $_2$ As $_2$，在低温下获得$ρ_c$ / $ρ_{ab}$高达130的各向异性电阻率。在200 K以下，由于SDW的不稳定性，观察到面内和面外电阻率的急剧下降。面内磁电阻的角度依赖性在低于SDW转变温度的ab平面内与场旋转呈现2重对称性。这与SDW态中的条纹型自旋有序相一致。在K掺杂的A $_{0.6}$ K $_{0.4}$ Fe $_2$ As $_2$（A= Sr. Ba）中，SDW不稳定性被抑制，在35 K以上出现超导电性，T $_c$。H $\parallel$ ab和H $\parallel$ c的上临界场各向异性很小，表明面间耦合在空穴掺杂铁基超导体中起着重要作用。
CeCd$_3$P$_3$ and CeCd$_3$As$_3$ compounds adopt the hexagonal ScAl$_3$C$_3$-type structure, where magnetic Ce ions on a triangular lattice order antiferromagnetically below $T_\text{N} \sim$0.42~K. Their crystalline electric field (CEF) level scheme has been determined by fitting magnetic susceptibility curves, magnetization isotherms, and Schottky anomalies in specific heat. The calculated results, incorporating the CEF excitation, Zeeman splitting, and molecular field, are in good agreement with the experimental data. The CEF model, with Ce$^{3+}$ ions in a trigonal symmetry, explains the s…
Magnetic Field Effect on Crossover Temperature from Non-Fermi Liquid to Fermi Liquid Behavior in f^2-Impurity Systems with Crystalline-Electric-Field Singlet State Competing with Kondo-Yosida Singlet State
We have studied the magnetic torque in uranium monosulfide (US) single crystals to explore the magnetic anisotropy in this material. Uranium monosulfide crystallizes in cubic, NaCl-type of crystal structure and exhibits the largest magneto-crystalline anisotropy observed in cubic systems. By performing detailed torque measurements we observe a strongly anisotropic behavior in the paramagnetic phase due to crystal defects and quadrupolar pair interactions. Our studies also confirm the presence of a large anisotropy in the ferromagnetic state of the US system with the <100>, <111>, and <110> dir…
We propose an experimental method to examine the in-plane anisotropy of electronic structure in layered conductors. In the method, we measure the interlayer magnetoresistance as a function of in-plane magnetic field orientation. We applied it to an organic Dirac fermion system a-(BEDT-TTF)2I3 to experimentally determine the orientation of the anisotropic Dirac cones. It is concluded that the long axis of the elliptic constant-energy contours of the Dirac cone is tilted by approximately -30 deg from the crystalline a-axis to b-axis under hydrostatic pressures. Additionally, we observed a signat…
We have measured the magnetization of rare-earth chiral magnets Yb(Ni$_{1-x}$Cu$_x$)$_{3}$Al$_{9}$ for $x$=0 and 0.06 up to 14.5 T. Magnetization for the field direction $H \parallel c$, which is the hard axis at low temperatures and low fields, overtakes the easy axis magnetization for $H \perp c$ above $\sim$4 T. We analyzed this overtaking of the magnetization curves by considering a crystalline electric field model. It is shown that the $B_{66}$ term, which connects the $|\pm5/2 \rangle$ and the $|\mp7/2\rangle$ states through the off-diagonal matrix element, is responsible for the charact…
Thermodynamic and transport properties of single crystalline RCo$_{2}$Ge$_{2}$ (R = Y, La-Nd, Sm-Tm)
使用自熔剂法生长RCo $_{2}$ Ge $_{2}$（R = Y、La-Nd、Sm-Tm）的单晶，并通过室温粉末X射线衍射、各向异性、温度和场依赖性磁化、温度和场依赖性、面内电阻率和比热测量来表征。在这个系列中，大多数的力矩轴承成员反铁磁有序; YCo $_{2}$ Ge $_{2}$和LaCo $_{2}$ Ge $_{2}$是非力矩轴承。Ce在高温下在CeCo $_{2}$ Ge $_{2}$中是三价的，并且在低温下由于近藤效应而表现出增强的电子比热系数。此外，CeCo $_{2}$ Ge $_{2}$在随温度变化的磁化强度和比热测量中显示出两个低温异常。三个成员（R = Tb-Ho）在1.8 K以上有多次相变。Eu似乎是二价的，总角动量L = 0。EuCo $_{2}$ Ge $_{2}$和GdCo $_{2}$ Ge $_{2}$都表现出与J = S = 7/2一致的基本上各向同性的顺磁性质。观察到具有有限L的稀土成员具有明显的磁各向异性，其中ErCo $_{2}$ Ge $_{2}$和TmCo $_{2}$ Ge $_{2}$表现出平面各向异性，其余成员表现出轴向各向异性。根据各向异性顺磁$θ_{ab}$和$θ_{c}$值计算了实验估计的晶体电场（CEF）参数B $_{2}^{0}$，并遵循与理论预测一致的趋势。重稀土元素的有序化温度T $_{N}$和多晶平均顺磁居里…
Detailed magnetization, specific heat, and $^7$Li nuclear magnetic resonance (NMR) measurements on single crystals of the hyperhoneycomb Kitaev magnet $β$-Li$_2$IrO$_3$ are reported. At high temperatures, {\cred anisotropy of the magnetization is reflected by the different Curie-Weiss temperatures for different field directions}, in agreement with the combination of a ferromagnetic Kitaev interaction ($K$) and a negative off-diagonal anisotropy ($Γ$) as two leading terms in the spin Hamiltonian. At low temperatures, magnetic fields applied along $a$ or $c$ have only a weak effect on the system…
