二维磁性系统和准一维磁性纳米管的内能

Intrinsic Energies of Two-dimensional Heisenberg Magnets and Ferromagnetic Single-walled Nanotubes

采用量子统计理论的多体格林函数法计算二维单离子各向异性海森伯铁磁体、反铁磁体以及单壁铁磁纳米管的内能,对比铁磁体和反铁磁体的结果.在相同的参量下,反铁磁能量总是低于相应的铁磁能量(相变点除外).由于反铁磁能量随温度上升的速度较铁磁能量快,当温度升高到居里点TC和奈尔点TN时(TC=TN),铁磁能量和反铁磁能量相等.横向关联效应对系统内能的影响较大,不能忽略.

Intrinsic energy of two-dimensional square lattice single-ion anisotropic Heisenberg ferromagnets, antiferromagnets, and ferromagnetic single-walled nanotubes are calculated with many-body Green’ s function method in quantum statistical theory. Calculated results of ferromagnets and antiferromagnets are compared. Between zero temperature and phase transition point, including zero temperature, anti-ferromagnetic energy is always lower than that of ferromagnetic energy. Calculation method of intrinsic energy in this paper is applicable not only to ferromagnetic system, but also suitable for antiferromagnetic system and ferrimagnetic system, as well as ferromagnetic single-walled nanotubes. Intrinsic energies are greatly lower than classical energies, which shows that transverse correlation effect is important.