We compare theoretical results for electron spin resonance (ESR) properties of the Heisenberg-Ising Hamiltonian with ESR experiments on the quasi-one-dimensional magnet Cu(py)$_2$Br$_2$ (CPB). Our measurements were performed over a wide frequency and temperature range giving insight into spin dynamics, spin structure, and magnetic anisotropy of this compound. By analyzing the angular dependence of ESR parameters (resonance shift and linewidth) at room temperature we show that the two weakly coupled inequivalent spin chain types inside the compound are well described by Heisenberg-Ising chains with their magnetic anisotropy axes perpendicular to the chain direction and almost perpendicular to each other. We further determine the full $g$-tensor from these data. In addition, the angular dependence of the linewidth at high temperatures gives us access to the exponent of the algebraic decay of a dynamical correlation function of the isotropic Heisenberg chain. From the temperature dependence of static susceptibilities we extract the strength of the exchange coupling ($J/k_B = 52.0\,\text{K}$) and the anisotropy parameter ($δ\approx -0.02$) of the model Hamiltonian. An independent compatible value of $δ$ is obtained by comparing the exact prediction for the resonance shift at low temperatures with high-frequency ESR data recorded at $4\,\text{K}$. The spin structure in the ordered state implied by the two (almost) perpendicular anisotropy axes is in accordance with the propagation vector determined from neutron scattering experiments. In addition to undoped samples we study the impact of partial substitution of Br by Cl ions on spin dynamics. From the dependence of the ESR linewidth on doping level we infer an effective decoupling of the anisotropic component $Jδ$ from the isotropic exchange $J$ in these systems.
Anisotropic Monopole Heat Transport in the Spin-Ice Compound Dy$_2$Ti$_2$O$_7$
本文报道了自旋冰材料Dy $_2$ Ti $_2$ O $_7$的热导率$κ$的研究。从κ $ and by additional measurements on the phononic reference compounds Y$ _2 PDMATHABMQ_2 PDMATHABMR_7 PDMATHABMS_2 PDMATHABMR_7 $, we are able to separate the phononic and the magnetic contributions to the total heat transport, i.e. $ κ_{ph} $ and $ κ_{mag} $, respectively, which both depend on the magnetic field. The field dependent $ κ_{ph} $ arises from lattice distortions due to magnetic-field induced torques on the non-collinear magnetic moments of the Dy ions. For $ κ_{mag} $, we observe a highly anisotropic magnetic-field dependence, which co…
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。
Static and Dynamic Magnetic Properties of Spin-1/2 Inequilateral Diamond-Chain Compounds $A_3$Cu$_3$AlO$_2$(SO$_4$)$_4$ ($A$=K, Rb, and Cs)
自旋为1/2的化合物A3 Cu 3AlO 2（SO 4）4（A=K，Rb，Cs）具有一维不等边金刚石链。我们分析了磁化率的温度依赖性，并确定磁交换相互作用。与蓝铜矿相反，二聚体形成在金刚石的一侧。通过对模型的数值分析，我们发现二聚体和一个近似孤立的一维海森堡链共同表征了磁性，包括磁化曲线和磁激发。这意味着，没有挫折的二聚体-单体复合物链是描述这些化合物的良好起点。
Incommensurate spin density modulation in a copper-oxide chain compound with commensurate charge order
中子衍射已被用来确定的磁性结构的Na $_8$ Cu $_5$ O $_{10}$，一个化学计量的化合物，含有链的基础上共享边缘CuO $_4$斑块。该链掺杂有2/5孔每个Cu网站，并表现出长程相称的电荷秩序与发病远高于室温。低于$T_N = 23$ K，中子数据表明长程共线磁序与自旋密度调制，其传播矢量是相称的沿和不相称的垂直链。竞争链间交换相互作用进行了讨论，作为一个可能的起源的无公度磁秩序。
用浮区法生长了新化合物SrMn $_2$ V $_2$ O $_8$的大单晶。该过渡金属基氧化物与SrNi $_2$ V $_2$ O $_8$同构，由四元空间群$I4_1cd$描述。通过磁化率，磁化强度和比热测量的磁性能进行了研究。标题化合物在有序温度（$T_N$ = 43 K）以上表现为一维磁性体系。磁基态可以描述为一个经典的长程有序反铁磁体，具有弱的各向异性。
Anisotropic physical properties of PrRhAl$_4$Si$_2$ single crystal a non-magnetic singlet ground state compound
我们已经生长出PrRhAl $_4$ Si $_2$的单晶，其以四方晶体结构结晶。从低温物理性质的测量，如，磁化率，磁化强度，热容和电阻率，我们发现，该化合物不显示任何磁有序低至70 mK。通过对样品磁化率和比热测量的晶场计算表明，PrRhAl $_4$ Si $_2$中Pr原子的9重简并$(2J+1)$能级在123 K处分裂为7个能级，其中有一个单重态基态和一个分离良好的激发二重态，总能级分裂能为320 K.
Low temperature ballistic spin transport in the S=1/2 antiferromagnetic Heisenberg chain compound SrCuO2
我们报道了自旋S=1/2反铁磁海森堡链材料SrCuO 2的零磁场和纵向磁场μ子自旋弛豫测量结果。我们发现，在弱的外加磁场B中，自旋-晶格弛豫速率服从幂律B^n，其中n=-0.9（3）。该结果对于5 K < T < 300 K是温度无关的。在共形场论和使用Müller的计算，我们得出弹道自旋输运SrCuO 2。
Helicoidal magnetic order in a clean copper oxide spin chain compound
我们报告的磁化率，比热，和中子衍射测量NaCu $_2$ O $_2$，自旋1/2链化合物同构的LiCu $_2$ O $_2$，这已被广泛研究。在13 K以下，我们发现了一个长程有序的、无公度的磁螺旋态，其传播矢量与LiCu $_2$ O $_2$的传播矢量相似.与Li类似物相比，NaCu $_2$ O $_2$中的取代无序可忽略不计。因此，我们可以排除螺旋是由杂质诱导的，正如先前对LiCu $_2$ O $_2$的工作所声称的那样。一个自旋哈密顿与挫折长程交换相互作用提供了一个很好的描述有序状态和顺磁磁化率。
Tomonaga-Luttinger spin liquid in the spin-1/2 inequilateral diamond-chain compound K$_3$Cu$_3$AlO$_2$(SO$_4$)$_4$
K $_3$ Cu $_3$ AlO $_2$（SO $_4$）$_4$是一种高度一维的自旋为1/2的不等边金刚石链反铁磁体。在非弹性中子散射谱中观察到自旋连续谱和自旋单重态二聚体激发，这与理论预测非常一致：二聚体-单体复合结构，其中二聚体由强反铁磁（AFM）耦合引起，单体形成几乎孤立的量子AFM链控制低能激发。此外，μ子自旋旋转/弛豫光谱显示没有长程有序下降到90 mK，这是大约三个数量级低于量子原子力显微镜链的交换相互作用。因此，K $_3$ Cu $_3$ AlO $_2$（SO $_4$）$_4$被认为是在接近基态的低温下表现出Tomonaga-Luttinger自旋液体行为的化合物。
Magnetization plateau and anisotropic magnetoresistance in the frustrated Kondo-lattice compound Ce3ScBi5
Northeastern University（东北大学）；University of Chinese Academy of Sciences（中国科学院大学）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；Southern University of Science and Technology（南方科技大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）
