HYDRODYNAMIC THEORY OF SPIN WAVES
HYDRODYNAMIC THEORY OF SPIN WAVES
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DOI：
10.1103/physrev.188.898
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发表时间：
1969-01-01
期刊：
影响因子：
--
通讯作者：
HOHENBER.PC
中科院分区：
文献类型：
--
作者：
HALPERIN, BI;HOHENBER.PC
本文发展了某些磁系统的自旋波流体力学理论，类似于液氦的双流体流体力学的推导。所考虑的系统是“各向同性”和“平面”铁磁体和反铁磁体。在每个系统中，低频自旋波预测存在于长波长的任何温度下的顺磁相的过渡。频率的真实的部分用热力学量精确地给出。在每种情况下，阻尼率与频率的真实的部分的平方成比例，因此与真实的部分相比，在长波长极限中可以忽略不计。这些结果的阻尼率是新的，不同意以前的海森堡铁磁体和反铁磁体的微观计算。提出了一个利用中子衍射的实验来检验几乎各向同性反铁磁体RbMnF3中的流体动力学理论。推导流体动力学理论所需的假设进行了详细讨论，是理论的有效性的限制，以及适用于真实的系统的结果。
A hydrodynamic theory of spin waves is developed for certain magnetic systems in analogy with the derivation of two-fluid hydrodynamics for liquid helium. The systems considered are" isotropic" and" planar" ferromagnets and antiferromagnets. In each system, low-frequency spin waves are predicted to exist at long wavelengths for any temperature below the transition to the paramagnetic phase. The real part of the frequency is given exactly in terms of thermodynamic quantities. The damping rate is proportional to the square of the real part of the frequency in each case, and hence is negligible in the long-wavelength limit, compared to the real part. These results for the damping rates are new, and disagree with previous microscopic calculations for the Heisenberg ferromagnet and antiferromagnet. An experiment using neutron diffraction is proposed to test the hydrodynamic theory in the almost isotropic antiferromagnet RbMn F 3. The assumptions necessary to derive the hydrodynamic theory are discussed in detail, as are the limits of validity of the theory, and the applicability of the results to real systems.