The Kagome-lattice-based material, Volborthite, $\mathrm{Cu_3 V_2 O_7 (OH)_2 \cdot 2 H_2 O}$, has been considered as a promising platform for discovery of unusual quantum ground states due to the frustrated nature of spin interactions. Here we explore possible quantum spin liquid and magnetically ordered phases in a two-dimensional non-symmorphic lattice described by $p2gg$ layer space group, which is consistent with the spatial anisotropy of the spin model derived from density functional theory (DFT) for Volborthite. Using the projective symmetry group (PSG) analysis and Schwinger boson mean field theory, we classify possible spin liquid phases with bosonic spinons and investigate magnetically ordered phases connected to such states. It is shown, in general, that only translationally invariant mean field states are allowed in two-dimensional non-symmorphic lattices, which simplifies the classification considerably. The mean field phase diagram of the DFT-derived spin model is studied and it is found that possible quantum spin liquid phases are connected to two types of magnetically ordered phases, a coplanar incommensurate $(q,0)$ spiral order as the ground state and a closely competing coplanar commensurate $(π,π)$ spin density wave order. In addition, periodicity enhancement of the two-spinon continuum, a signature of symmetry fractionalization, is found in the spin liquid phases connected to the $(π,π)$ spin density wave order. We discuss relevance of these results to recent and future experiments on Volborthite.
Pair Correlations, Short Range Order and Dispersive Excitations in the Quasi-Kagome Quantum Magnet Volborthite
我们目前的空间和动态信息的s=1/2扭曲kagome反铁磁volborthite，Cu 3V 2 O 7（OD）2.2D2O，通过极化和非弹性中子散射。瞬时结构因子S（Q）主要由最近邻对相关决定，在5 K以下出现波矢量Q1=0.65（3）<$^-1和Q2=1.15（5）<$^-1的短程有序。激发谱S（Q，ω）显示出从Q1和Q2分散的两个陡峭的分支和在ω=5.0（2）meV处的平坦模。结果使我们能够确定在T*=1 K的51 V NMR和比热测量的交叉作为在Q_1的相关性的建立。我们比较我们的数据提出的理论模型为volborthite，并表明，激发光谱可以解释自旋波类激发各向异性交换参数，最近的局部密度计算也建议。
We determined the spin exchanges between the Cu2+ ions in the kagome layers of volborthite, Cu3V2O7(OH)2x2H2O, by performing the energy-mapping analysis based on DFT+U calculations, to find that the kagomé layers of Cu2+ ions are hardly spin-frustrated, and the magnetic properties of volborthite below ~75 K should be described by very weakly interacting antiferromagnetic uniform chains made up of effective S=1/2 pseudospin units. This conclusion was verified by synthesizing single crystals of not only Cu3V2O7(OH)2x2H2O but also its deuterated analogue Cu3V2O7(OD)2x2D2O and then by investigatin…
Motivated by a recent experiment on volborthite, a typical spin-$1/2$ antiferromagnet with a kagomé lattice structure, we study the magnetization process of a classical Heisenberg model on a spatially distorted kagomé lattice using the Monte Carlo (MC) method. We find a distortion-induced magnetization step at low temperatures and low magnetic fields. The magnitude of this step is given by $Δm_z=\left|1-α\right|/3α$ at zero temperature, where $α$ denotes the spatial anisotropy in exchange constants. The magnetization step signals a first-order transition at low temperatures, between two phases…
Coupled frustrated quantum spin-1/2 chains with orbital order in volborthite Cu3V2O7(OH)2(H2O)2
我们提出了一个微观磁性模型的自旋液体候选volborthite Cu 3V 2 O 7（OH）2（H2O）2。这个基于DFT的模型的要点是（i）Cu（1）3d 3 z2-r2和Cu（2）3d 3x 2-y2的轨道有序，（ii）三个相关的耦合Jic，J1和J2，（iii）J1的铁磁性质和（iv）次近邻交换相互作用J2控制的阻挫。我们的模型意味着磁性的挫折耦合链在以前提出的各向异性kagome模型。精确的对角化研究表明与实验一致。
