Haghshenasfard Zahra, Cottam M G
Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7, Canada.
J Phys Condens Matter. 2017 May 17;29(19):195801. doi: 10.1088/1361-648X/aa67a3. Epub 2017 Mar 20.
A microscopic (Hamiltonian-based) method for the quantum statistics of bosonic excitations in a two-mode magnon system is developed. Both the exchange and the dipole-dipole interactions, as well as the Zeeman term for an external applied field, are included in the spin Hamiltonian, and the model also contains the nonlinear effects due to parallel pumping and four-magnon interactions. The quantization of spin operators is achieved through the Holstein-Primakoff formalism, and then a coherent magnon state representation is used to study the occupation magnon number and the quantum statistical behaviour of the system. Particular attention is given to the cross correlation between the two coupled magnon modes in a ferromagnetic nanowire geometry formed by two lines of spins. Manipulation of the collapse-and-revival phenomena for the temporal evolution of the magnon number as well as the control of the cross correlation between the two magnon modes is demonstrated by tuning the parallel pumping field amplitude. The role of the four-magnon interactions is particularly interesting and leads to anti-correlation in some cases with coherent states.
开发了一种用于双模磁振子系统中玻色子激发量子统计的微观（基于哈密顿量）方法。自旋哈密顿量中包含了交换相互作用、偶极 - 偶极相互作用以及外磁场的塞曼项，并且该模型还包含了由平行泵浦和四磁振子相互作用引起的非线性效应。通过霍尔斯坦 - 普里马科夫形式实现自旋算符的量子化，然后使用相干磁振子态表示来研究系统的占据磁振子数和量子统计行为。特别关注由两行自旋形成的铁磁纳米线几何结构中两个耦合磁振子模式之间的交叉关联。通过调节平行泵浦场幅度，展示了对磁振子数时间演化的塌缩 - 复苏现象的操控以及对两个磁振子模式之间交叉关联的控制。四磁振子相互作用的作用特别有趣，并且在某些情况下会导致与相干态的反关联。
