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arXiv 1208.3989cond-mat.str-el
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各向异性kagome晶格上自旋为1/2的海森堡反铁磁体

Spin-1/2 Heisenberg antiferromagnet on an anisotropic kagome lattice

P. H. Y. Li, R. F. Bishop, C. E. Campbell, D. J. J. Farnell, O. Götze, J. Richter

发表信息：
Physical Review B 86, 214403 (2012)
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摘要：

我们使用耦合团簇方法研究了由自旋为1/2的磁矩在无限空间各向异性的等腰三角形kagome晶格上形成的扩展的二维海森堡反铁磁体的零温度性质，其中只有最近邻键。这些键沿三个晶格方向中的两个方向具有交换常数$J_{1}>0$，沿第三个方向具有交换常数$J_{2} \equiv κJ_{1} > 0$。在经典极限下，$κ< 1/2$的基态（GS）相位具有共线亚铁磁（Néel $'$）序，其中$J_2$耦合链自旋在一个方向上铁磁有序，其余自旋在相反方向上排列，而对于$κ> 1/2$，存在无限的倾斜亚铁磁自旋态GS家族，其能量简并。对于自旋1/2的情况下，我们发现，这两个经典状态的量子类似物继续存在的各向异性参数$κ$的某些区域，即$0<κ<κ_{c_1}$的Néel $'$状态和（至少部分）的区域$κ>κ_{c_2}$的倾斜相稳定的GS相。然而，它们现在被在区域$κ_{c_1} < κ< κ_{c_2}$中没有任何磁序的顺磁相分开，该区域包括各向同性的可果美点$κ= 1$，其中稳定的GS相现在被认为是拓扑（$\mathbb{Z}_2$）自旋液体。我们的最佳数值估计是$κ_{c_1} = 0.515 \pm 0.015$和$κ_{c_2} = 1.82 \pm 0.03$。

英文摘要：

We use the coupled cluster method to study the zero-temperature properties of an extended two-dimensional Heisenberg antiferromagnet formed from spin-1/2 moments on an infinite spatially anisotropic kagome lattice of corner-sharing isosceles triangles, with nearest-neighbor bonds only. The bonds have exchange constants $J_{1}>0$ along two of the three lattice directions and $J_{2} \equiv κJ_{1} > 0$ along the third. In the classical limit the ground-state (GS) phase for $κ< 1/2$ has collinear ferrimagnetic (Néel$'$) order where the $J_2$-coupled chain spins are ferromagnetically ordered in one direction with the remaining spins aligned in the opposite direction, while for $κ> 1/2$ there exists an infinite GS family of canted ferrimagnetic spin states, which are energetically degenerate. For the spin-1/2 case we find that quantum analogs of both these classical states continue to exist as stable GS phases in some regions of the anisotropy parameter $κ$, namely for $0<κ<κ_{c_1}$ for the Néel$'$ state and for (at least part of) the region $κ>κ_{c_2}$ for the canted phase. However, they are now separated by a paramagnetic phase without either sort of magnetic order in the region $κ_{c_1} < κ< κ_{c_2}$, which includes the isotropic kagome point $κ= 1$ where the stable GS phase is now believed to be a topological ($\mathbb{Z}_2$) spin liquid. Our best numerical estimates are $κ_{c_1} = 0.515 \pm 0.015$ and $κ_{c_2} = 1.82 \pm 0.03$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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