在有效Ising自旋为1/2的反铁磁链系统BaCo $_2$ V $_2$ O $_8, the magnetic-field influence is highly anisotropic. For magnetic fields along the easy axis $ c $, the Néel order is strongly suppressed already for low fields and an incommensurate order is entered above 4 T. We present a detailed study of the magnetic phase diagrams for different magnetic field directions, which are derived from magnetization data, high-resolution thermal expansion and magnetostriction measurements as well as from the thermal conductivity. Zero-field thermal expansion data reveal that the magnetic transition is accompanied by an orthorhombic distortion within the $ ab $ plane. Under ambient conditions the crystals are heavily twinned, but the domain orientation can be influenced either by applying uniaxial pressure or a magnetic field along the [100] direction. In addition, our data reveal a pronounced in-plane magnetic anisotropy for fields applied within the $ ab $ plane. For $ H|| [110] $, the magnetic field influence on T$ _N $ is weak, whereas for magnetic fields applied along [100], T$ _N $ vanishes at about 10 T and the zero-field Néel order is completely suppressed as is confirmed by neutron diffraction data. The second-order phase transition strongly suggests a quantum critical point being present at $ H \simeq 10$ T平行[100]，其中Néel顺序可能变为自旋液体状态。
英文摘要：
In the effective Ising spin-1/2 antiferromagnetic chain system BaCo$_2$V$_2$O$_8, the magnetic-field influence is highly anisotropic. For magnetic fields along the easy axis $c$, the Néel order is strongly suppressed already for low fields and an incommensurate order is entered above 4 T. We present a detailed study of the magnetic phase diagrams for different magnetic field directions, which are derived from magnetization data, high-resolution thermal expansion and magnetostriction measurements as well as from the thermal conductivity. Zero-field thermal expansion data reveal that the magnetic transition is accompanied by an orthorhombic distortion within the $ab$ plane. Under ambient conditions the crystals are heavily twinned, but the domain orientation can be influenced either by applying uniaxial pressure or a magnetic field along the [100] direction. In addition, our data reveal a pronounced in-plane magnetic anisotropy for fields applied within the $ab$ plane. For $H || [110]$, the magnetic field influence on T$_N$ is weak, whereas for magnetic fields applied along [100], T$_N$ vanishes at about 10 T and the zero-field Néel order is completely suppressed as is confirmed by neutron diffraction data. The second-order phase transition strongly suggests a quantum critical point being present at $H\simeq 10$ T parallel [100], where the Néel order probably changes to a spin-liquid state.
Revealing a Triangular Lattice Ising Antiferromagnet in a Single-Crystal CeCd$_3$As$_3$
本文报道了稀土三角晶格反铁磁体CeCd $_3$ As $_3$的单晶生长和基本磁性及热力学性质。在这种稀土反铁磁体中，Ce局域磁矩形成了一个完美的三角晶格。由于Ce局域磁矩的自旋-轨道纠缠性质，该化合物分别沿c方向和ab平面表现出极其各向异性的反铁磁耦合。我们表明，铈镉$_3$作为$_3$代表一个{ \it罕见}的实验实现的反铁磁伊辛模型的二维三角晶格，从而提供了一个原型的例子几何挫折。我们进一步讨论了微扰相互作用在主导伊辛相互作用之上的量子效应。
Exact evidence for the spontaneous antiferromagnetic long-range order in the two-dimensional hybrid model of localized Ising spins and itinerant electrons
Frustration and Correlations in Stacked Triangular Lattice Ising Antiferromagnets
我们研究多层三角晶格伊辛反铁磁体层间的相互作用是弱的和挫折的abc堆叠。通过分析这些系统的耦合高度模型的描述，我们表明，它们表现出一个经典的自旋液体制度在低温下，其中层内和层间的相关性很强，但没有长程序。在这种情况下，漫散射集中在倒易空间的螺旋上，如在材料LuFe $_2$ O $_4$和YbFe $_2$ O $_4$中观察到的电荷有序。
Spin-liquid behaviour and the interplay between Pokrovsky-Talapov and Ising criticality in the distorted, triangular-lattice, dipolar Ising antiferromagnet
Spinon Confinement in the One-Dimensional Ising-Like Antiferromagnet SrCo2V2O8
对于准一维量子自旋系统，理论预言由于链间耦合，自旋子的激发会受到限制。在这里，我们调查系统SrCo 2 V 2 O 8，实现弱耦合Ising类XXZ反铁磁链，太赫兹光谱与无外加磁场。在低温下，观察到一系列的激发，分裂在一个塞曼样的方式在一个施加的磁场。这些磁激发被确定为理论预测的自旋对激发。利用一维薛定谔方程和由弱链间耦合作用产生的线性禁闭势，可以完整地描述禁闭自旋子的层次结构。
Field-tuned order by disorder in Ising frustrated magnets with antiferromagnetic interactions
我们证明了在具有交错反铁磁序的伊辛高温超导体中，在外加磁场的作用下，无序的热有序的出现。我们使用平均场集团变分法、低温展开和蒙特卡罗模拟来模拟有序-无序转变。通过对态密度的直接计算，我们定量地说明了热激发如何选择一个破缺态。我们讨论了我们的研究结果的相关性，在$2d$和$3d$样品的实验，并评估如何异常的有限尺寸效应可以被利用来检测这种现象的实验在二维人工系统中，或在反铁磁的所有在-所有出pyropheres如Nd $_2$铪$_2$ O $_7$或Nd $_2$锆$_2$ O $_7$，为第一次。
Order-by-disorder and long-range interactions in the antiferromagnetic transverse-field Ising model on the triangular lattice -- A perturbative point of view
Observation of E8 Particles in an Ising Chain Antiferromagnet
在横场诱导的伊辛链量子临界点附近，预言了一个由8个粒子组成的奇异动力学谱，该谱由具有$E_8$李代数对称性的涌现量子可积场论唯一描述，但很少在实验上探索.在这里，我们使用高分辨率太赫兹光谱解决量子自旋动力学的准一维伊辛反铁磁体BaCo $_2$ V $_2$ O $_8$在施加的横向场。通过与动力学自旋关联的解析计算相比较，我们确定了$E_8$粒子以及它们的两粒子激发。
