Anisotropy effects on the magnetic properties of an S=1 antiferromagnetic Heisenberg chain.
Anisotropy effects on the magnetic properties of an S=1 antiferromagnetic Heisenberg chain.
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各向异性对 S=1 反铁磁海森堡链磁性的影响。
DOI：
10.1103/physrevb.50.6277
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Miyashita
中科院分区：
文献类型：
--
作者：
Yamamoto;Miyashita
单轴单离子各向异性 ${\mathit{tsum}}_{\mathit{i}}$${\mathit{D}}_{\mathit{z}}$(${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$${)}^{2}$ 对具有开放边界的 S=1 反铁磁海森堡链的磁特性的影响为通过量子蒙特卡罗方法研究。在地面站中，各向异性如何影响交错磁化强度<${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$>和自旋相关函数〈${\mathit{S}}_{1}^{\mathit{z}}$${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉 和研究了〈${\mathit{S}}_{1}^{\mathit{x}}$${\mathit{S}}_{\mathit{i}}^{\mathit{x}}$〉。 〈${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉的振幅随着${\mathit{D}}_{\mathit{z}}$的增加而减小。 〈${\mathit{S}}_{1}^{\mathit{z}}$${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉的相关长度${\ensuremath{\xi}}_{\mathit{S}\mathit{S}}^{\mathit{z}}$随着 的增加单调减小${\mathit{D}}_{\mathit{z}}$，而相关长度${\ensuremath{\xi}}_{\mathit{S}\mathit{S}}^{\mathit{x}}$为〈${\mathit{S}}_{1}^{\mathit{x}}$${\mathit{S}}_{\mathit{i}}^{\mathit{x}}$〉具有相反但弱的${\mathit{D}}_{\mathit{z}}$依赖性。基态的四重简并性在热力学极限中也适用于非零 ${\mathit{D}}_{\mathit{z}}$，尽管它在有限链中被提升。在有限温度下，计算沿 z 轴 (${\mathrm{\ensuremath{\chi}}}^{\mathit{z}}$) 和 x 轴 (${\mathrm{\ensuremath{\chi}}}^{\mathit{x}}$) 的磁化率。体磁化率 ${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\infty}}}^{\mathit{z}}$ 和 ${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\infty}}}^{\mathit{x}}$ 的温度依赖性与Ni(${\mathrm{C}}_{2}$${\mathrm{H}}_{8}$${\mathrm{N}}_{2}$${)}_{2}$${\mathrm{NO}}_{2}$${\mathrm{ClO}}_{4}$ (NENP) 的实验结果。有限尺寸修正 ${\mathrm{\ensuremath{\chi}}}_{0}^{\mathit{z}}$ 和 ${\mathrm{\ensuremath{\chi}}}_{0}^{\mathit{x}}$ 以及链末端产生的居里磁化率， ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}^{\mathit{z}}$ 和 ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}^{\mathit{x}}$ 也进行了详细研究。 ${\mathrm{\ensuremath{\chi}}}_{0}$ 和 ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}$ 都随着温度趋于零而发散，并且它们通过关系组合${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}$=${\mathrm{\ensuremath{\chi}}}_{0}$+${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\infty}}}$。 ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}$ 的温度依赖性在低温下由边缘效应主导，而在高温下则归因于 S=1 自由自旋。
Effects of an uniaxial single-ion anisotropy ${\mathit{tsum}}_{\mathit{i}}$${\mathit{D}}_{\mathit{z}}$(${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$${)}^{2}$ on the magnetic properties of an S=1 antiferromagnetic Heisenberg chain with open boundaries are studied by a quantum Monte Carlo method. In the ground stae, how the anisotropy affects the staggered magnetization 〈${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉 and the spin correlation functions 〈${\mathit{S}}_{1}^{\mathit{z}}$${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉 and 〈${\mathit{S}}_{1}^{\mathit{x}}$${\mathit{S}}_{\mathit{i}}^{\mathit{x}}$〉 is investigated. Amplitudes of 〈${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉 decrease with with increase of ${\mathit{D}}_{\mathit{z}}$. The correlation length ${\ensuremath{\xi}}_{\mathit{S}\mathit{S}}^{\mathit{z}}$ of 〈${\mathit{S}}_{1}^{\mathit{z}}$${\mathit{S}}_{\mathit{i}}^{\mathit{z}}$〉 monotonously decreases with increase of ${\mathit{D}}_{\mathit{z}}$, while the correlation length ${\ensuremath{\xi}}_{\mathit{S}\mathit{S}}^{\mathit{x}}$ of 〈${\mathit{S}}_{1}^{\mathit{x}}$${\mathit{S}}_{\mathit{i}}^{\mathit{x}}$〉 has the opposite but weak ${\mathit{D}}_{\mathit{z}}$ dependence. The fourfold degeneracy of the ground state also holds with nonzero ${\mathit{D}}_{\mathit{z}}$'s in the thermodynamic limit although it is lifted up in finite chains. At finite temperatures, the magnetic susceptibilities along the z axis (${\mathrm{\ensuremath{\chi}}}^{\mathit{z}}$) and the x axis (${\mathrm{\ensuremath{\chi}}}^{\mathit{x}}$) are calculated. Temperature dependences of the bulk susceptibilites, ${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\infty}}}^{\mathit{z}}$ and ${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\infty}}}^{\mathit{x}}$, are consistent with the previous experimental result on Ni(${\mathrm{C}}_{2}$${\mathrm{H}}_{8}$${\mathrm{N}}_{2}$${)}_{2}$${\mathrm{NO}}_{2}$${\mathrm{ClO}}_{4}$ (NENP). Finite-size corrections, ${\mathrm{\ensuremath{\chi}}}_{0}^{\mathit{z}}$ and ${\mathrm{\ensuremath{\chi}}}_{0}^{\mathit{x}}$, and the Curie susceptibilities resulting from chain ends, ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}^{\mathit{z}}$ and ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}^{\mathit{x}}$, are also investigated in detail. Both ${\mathrm{\ensuremath{\chi}}}_{0}$ and ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}$ diverge as temperature goes to zero and they are combined through a relation ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}$=${\mathrm{\ensuremath{\chi}}}_{0}$+${\mathrm{\ensuremath{\chi}}}_{\mathrm{\ensuremath{\infty}}}$. Temperature dependences of ${\mathrm{\ensuremath{\chi}}}_{\mathit{C}}$ are dominated by the edge effect at low temperatures, while at high temperatures they are attributed to an S=1 free spin.