Spin‐Wave Theory of Principal Susceptibilities of the Heisenberg Antiferromagnet
Spin‐Wave Theory of Principal Susceptibilities of the Heisenberg Antiferromagnet
复制标题
海森堡反铁磁体主磁化率的自旋波理论
DOI：
10.1063/1.1656303
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发表时间：
1968
影响因子：
3.2
通讯作者：
Y. Itoh
中科院分区：
文献类型：
--
作者：
J. Kanamori;Y. Itoh
由Trapp和Stout测量的MnF 2在TN（67.3°K）以下的垂直磁化率在低温下随温度的升高而减小，并在45°K处达到最小值。与数据相比，基于现有自旋波理论的磁化率计算在15°K以上下降得太快。通过一种新的方法指出，这些理论忽略了三个或更多有限波数的磁振子的激发所做的重要贡献;它们来自于外场扰动下自旋波相互作用的非对角部分。新的贡献开始于1/S膨胀中的1/S2项，并随温度增加。在40°K以下，考虑了1/S2的全部项的计算与实验数据符合得很好。还提出了平行磁化率的计算，该计算考虑了由外部场通过自旋波相互作用引起的自旋波频率的偏移。即使在50°K下，它也与实验相符。
The perpendicular susceptibility of MnF2 below TN(67.3°K) measured by Trapp and Stout decreases with increasing temperature at low temperatures and passes a minimum at 45°K. Calculation based on existing spin‐wave theories of the susceptibility turns out to decrease too fast above 15°K compared with the data. It is pointed out through a new approach that the theories neglect an important contribution made by excitations of three and more magnons of finite wavenumber; they arise from the nondiagonal part of the spin‐wave interaction with the perturbation of external field. The new contribution starts with a 1/S2 term in the 1/S expansion and increases with temperature. A calculation which takes into account whole terms of 1/S2 is in good agreement with the data up to 40°K. A calculation of the parallel susceptibility is also presented, which takes into account a shift of the spin‐wave frequency caused by external field through the spin‐wave interaction. It agrees with experiment even at 50°K.