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arXiv 2010.06258cond-mat.str-el
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在次近邻耦合和Dzyaloshinskiii-Moriya相互作用下交替自旋- $\frac{1}{2}$ /自旋- $1$链的经典性损失

Loss of classicality in alternating spin-$\frac{1}{2}$/spin-$1$ chain, in the presence of next-neighbor couplings and Dzyaloshinskii-Moriya interactions

Abhiroop Lahiri, Swapan K Pati

摘要:

我们考虑了最近邻($J_1$)、次最近邻($J_2$)反铁磁耦合以及Z分量的Dzyaloshinskiii-Moriya(DM)($D_z$)相互作用的交替海森堡自旋链。用线性自旋波理论(LSWT)和密度矩阵重整化群(DMRG)研究了哈密顿量。该系统以前曾被报道为经典的亚铁磁体,只有当最近邻交换相互作用。反铁磁次近邻相互作用和DM相互作用都引入了强烈的量子涨落,因此亚铁磁性的所有特征都消失了。我们发现非零的$J_2$在每个自旋位置引入了强的量子涨落,因此自旋1和自旋1/2位置的z分量平均为零。基态变为单重态。$J_1$和$D_z$的存在引入了短程有序,但沿XY平面形成了长程序。$J_1$与$J_2$一起诱导具有结构因子的竞争相,所述结构因子在两个不同角度处显示尖锐且宽的峰,所述两个不同角度反映了局部以及底层晶格中的自旋螺旋结构。有趣的是,我们发现,$D_z$项删除了本地自旋螺旋结构的z方向,而发展的螺旋秩序在XY平面。

英文摘要:

We have considered and alternating Heisenberg spin chain with nearest-neighbor ($J_1$), next-nearest neighbor ($J_2$) antiferromagnetic couplings along with z-component of the Dzyaloshinskii-Moriya(DM) ($D_z$) interactions. The Hamiltonian has been studied using (a) Linear Spin-Wave Theory(LSWT) and (b) Density Matrix Renormalization Group (DMRG). The system had been reported earlier as a classical ferrimagnet only when nearest neighbor exchange interactions are present. Both the antiferromagnetic next-nearest neighbor interactions and DM interactions introduce strong quantum fluctuations and due to which all the signatures of ferrimagnetism vanishes. We find that the nonzero $J_2$ introduces strong quantum fluctuations in each of the spin sites due to which the z-components of both spin-1 and spin-1/2 sites average out to be zero. The ground state becomes a singlet. The presence of $J_1$ along with $D_z$ introduces a short range order but develops long range order along the XY plane. $J_1$ along with $J_2$ induces competing phases with structure factor showing sharp and wide peaks, at two different angles reflecting the spin spiral structure locally as well as in the underlying lattice. Interestingly, we find that the $D_z$ term removes the local spin spiral structure in z-direction, while developing a spiral order in the XY plane.

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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