铁磁体中磁振子的压缩态

Squeezing states of magnons in a ferromagnet

研究了铁磁体中磁振子的压缩态.采用霍尔斯坦和普里马科夫提出的二次量子化方法把磁振子系统的哈密顿量简化,并应用平均场理论处理了哈密顿量中的非线性相互作用项;通过计算自旋涨落的平均值得到了产生压缩态的周期性条件;测得压缩态的周期,可得到铁磁材料的一些重要的物理量的信息,如交互积分等.实验表明,利用铁磁共振扩散实验可以检测磁振子的压缩态,压缩程度越大,共振吸收系数(RAC)越小.实验还表明,磁振子压缩态的量子涨落小于相干态时的量子涨落,这也提高了对可观测量的测量精度.

The squeezing states of magnons in a ferromagnet were studied, which originate from the nonlinear interaction of magnons. Hamiltonian of magnons system was simplified by the second quantization method presented by Holstein and Primakoff. The nonlinear interaction term of Hanitltonian was dealt with by mean theory. The condition of achieving the squeezing states of magnons in ferromagnet was found, after the mean value of the spin fluctuation calculated. If the period of achieving squeezing states was measured, some useful information of the ferromagnet material, such as the international integral, was got. The squeezing states of magnons in ferromagnet can be detected by ferromagnetic resonance scattering. The bigger the squeezing degree is, the smaller the resonance absorption coefficient （RAC） is. The quantum fluctuation of the magnons squeezing states is lower than that of the coherent states, useful to improve the precision of detection.