Effect of the Magnetic Field on the des Cloizeaux-Pearson Spin-Wave Spectrum
Effect of the Magnetic Field on the des Cloizeaux-Pearson Spin-Wave Spectrum
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磁场对 Cloizeaux-Pearson 自旋波谱的影响
DOI：
10.1143/ptp.57.1862
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发表时间：
1977
影响因子：
--
通讯作者：
H. Shiba
中科院分区：
文献类型：
--
作者：
N. Ishimura;H. Shiba
将S=1/2反铁磁海森堡链的自旋波谱的Des Cloizeaux和Pearson精确解推广到有限外场的情形。它自然地再现了零场极限下的Des Cloizeaux-Pearson谱，以及大于临界场的铁磁态的自旋波谱。通过与其他近似理论的预测结果的比较，对结果进行了讨论。在CuC12·2nc，D，这是一个典型的一维反铁磁海森堡自旋系统，S=1/2。他们用中子散射表明，它的自旋波谱与著名的Des Cloizeaux和Pearson(DC-P)和L的精确解符合得很好，而与安德森(分子场)理论不一致。它清楚地表明了对一维系统进行精确理论研究的重要性。虽然这个实验是在没有外加磁场的情况下进行的，但反铁磁线性链中基元激发的磁场依赖性将是非常有趣的。本文的目的是精确地研究DC-P自旋波谱的磁场依赖关系。我们希望这项工作能促进对外场作用下一维海森堡反铁磁体动力学的进一步实验研究。基于LD-Heisenberg模型的费米子表示5L.Bl，L应用Bulaevskii(Hartree-Fock)近似计算了LD-Heisenberg反铁磁体自旋波的场依赖性。我们后来将其与我们的结果进行了比较。我们还表明DC-P自旋波的磁场依赖性与经典的(Anderson)自旋波的磁场依赖性有本质的不同。公式和计算的细节给出在§2。
The des Cloizeaux and Pearson's exact solution for the spin-wave spectrum of the S=1/2 antiferromagnetic Heisenberg chain is extended to the case of finite external field. It reproduces naturally the des Cloizeaux-Pearson spectrum in the zero-field limit as well as the spin-wave spectrum in the ferromagnetic state for fields larger than the critical field. The results are discussed by comparing them with predictions of other approximate theories. on CuC12 • 2NC,D,, which is a typical 1D antiferromagnetic Heisenberg spin system with S = 1/2. They showed by neutron scattering that its spin-wave spectrum agrees quite well with the celebrated exact solution of des Cloizeaux and Pearson ( dC-P) ;l and is in disagreement with the Anderson (molecular-field) theory. It clearly demonstrates the importance of exact theoretical studies of 1D systems. Although this experiment was made in the absence of external magnetic field, the magnetic-field dependence of elementary excitations in antiferromagnetic linear chains would be very interesting. The purpose of this paper is to study exactly the magnetic-field dependence of the dC-P spin-wave spectrum. We hope that this work would stimulate further experimental studies on dynamics of 1D Heisenberg antiferromagnets in the presence of external field. The field dependence of spin waves of lD Heisenberg antifer romagnets has previously been calculated by Pytte,"l who applied the Bulaevskii (Hartree-Fock) approximation') based on the Fermion representation 5l.Bl of the lD Heisenberg model. We later compare it with our result. We also show that the magnetic-field dependence of the dC-P spin wave is qualitatively different from that of the classical (Anderson) spin wave. The details of the formulation and calculations are presented in § 2. Com-