单原子层磁性纳米带的自旋波谱

本文利用量子统计理论的多体格林函数方法计算了单原子层磁性纳米带的自旋波的色散关系。带宽为L的纳米带,其自旋波能谱有L条,自旋波能量随温度的升高而降低。温度接近居里点时,自旋波能量趋于零,可以称之为模式的软化。零温时,准一维纳米带体系的自旋波能量曲线随带宽的变宽而上升,最后趋于二维平面的数值。把单原子层磁性纳米带与单壁磁性纳米管的自旋波能谱做比较,前者的自旋波能量是非简并的,后者是简并的。自旋波能量简并在物理上是由对称性所致,与纳米管相比,纳米带的几何对称性明显降低了。

Spin Waves in Ferromagnetic Monolayer Nanobelts

In this paper, the spin wave spectra of ferromagnetic nanobehs are investigated by means of the the many-body Green＇ s function method of quantum statistical theory. For a nanobeh with width L, there are L branches of energy spectra, toy = ω （p） ,v = 1,2, ...L. A higher temperature leads to lower energy spectra. The spin-wave energy to（p） drops with temperature rising, and becomes zero as temperature reaches Tc, which is so-called the mode softening. At zero temperature, the spin-wave energy is dependent of belt-width,which increases with L rising, and approaches that of a 2D monolayer. Comparing the results of spin wave energy spectra of a single-layered nanobeh with those of a single-walled nanotube, we found that the spectra of the former are non-degenerate. In contrary to that, the spectra of the latter are degenerate. Physically, the degeneracy of the energies is caused by the symmetry. Compared to a nanotube, the symmetry of a nanobelt is reduced significantlv.