DYNAMICAL CORRELATION-FUNCTIONS IN A ONE-DIMENSIONAL ISING-LIKE ANTI-FERROMAGNETIC CSCOCL3 - A NEUTRON-SCATTERING STUDY
DYNAMICAL CORRELATION-FUNCTIONS IN A ONE-DIMENSIONAL ISING-LIKE ANTI-FERROMAGNETIC CSCOCL3 - A NEUTRON-SCATTERING STUDY
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DOI：
10.1103/physrevb.23.2298
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发表时间：
1981-01-01
影响因子：
3.7
通讯作者：
SHIRANE, G
中科院分区：
文献类型：
--
作者：
YOSHIZAWA, H;HIRAKAWA, K;SHIRANE, G
通过非弹性中子散射研究一维 (1D) 反铁磁体 CsCo Cl 3 中的自旋动力学。我们报告了 Villain 预测的一维反铁磁畴壁传播模式的第一个实验证据。与通常的洛伦兹线形状不同，在 S zz (q, ω) 中，当 q>~ κ 时，在 ω= 0 附近可以看到特征肩部。该肩仅在高温下出现，这表明肩强度与热激活畴壁的数量相对应。 Ishimura 和 Shiba 的理论计算表明，一维反铁磁体畴壁运动也会影响自旋波谱。观察到的光谱由一维反铁磁畴壁运动引起的非简并磁振子态的激发连续体组成。使用色散公式 ℏ ω q= 2 J (1− 8 ε 2 cos 2 q c)，我们评估交换 2 J 和 ε 分别为 12.75±0.1 meV 和 0.14±0.02。这些值可以描述激励连续体的两个边界 2 J±4 ε J|余弦qc|以及 S zz (q, ω), 4 ε J| 中的肩部位置sin q c|，正确。然而，向低能量侧具有高谱密度的自旋波线形状的不对称性比理论预测更加增强。
Spin dynamics in a one-dimensional (1D) antiferromagnet CsCo Cl 3 is studied by inelastic neutron scattering. We report the first experimental evidence for a propagative mode of 1D antiferromagnetic domain walls predicted by Villain. Instead of a usual Lorentzian line shape, a characteristic shoulder can be seen in S zz (q, ω) near ω= 0 for q>~ κ. This shoulder appears only at elevated temperatures, which indicates that the shoulder intensity corresponds to the number of thermally activated domain walls. The 1D antiferromagnet domain-wall motion can also affect the spin-wave spectrum as shown by theoretical calculation of Ishimura and Shiba. The observed spectrum consists of the excitation continuum of nondegenerate magnon states due to the motion of 1D antiferromagnet domain walls. Using the dispersion formula ℏ ω q= 2 J (1− 8 ε 2 cos 2 q c), we evaluate the exchange 2 J and ε to be 12.75±0.1 meV and 0.14±0.02, respectively. These values can describe both the boundaries of the excitation continuum 2 J±4 ε J| cos q c| and the shoulder position in S zz (q, ω), 4 ε J| sin q c|, correctly. The asymmetry of the spin-wave line shapes with heavy spectral density towards the lower-energy side, is, however, more enhanced than the theoretical prediction.