Datta Sambhu N, Panda Anirban
Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India.
J Phys Condens Matter. 2009 Aug 19;21(33):336003. doi: 10.1088/0953-8984/21/33/336003. Epub 2009 Jul 24.
We present an all-temperature magnon formalism for ferromagnetic solids. To our knowledge, this is the first time that all-temperature spin statistics have been calculated. The general impression up to now is that the magnon formalism breaks down at the Curie point as it introduces a series expansion and unphysical states. Our treatment is based on an accurate quantum mechanical representation of the Holstein-Primakoff transformation. To achieve this end, we introduce the 'Kubo operator'. The treatment is valid for all 14 types of Bravais lattices, and not limited to simple cubic unit cells. In the present work, we carry out a zeroth-order treatment involving all possible spin states, and leaving out all unphysical states. In a subsequent paper we will show that the perturbed energy values are very different, but the magnetic properties undergo only small modifications from the zeroth-order results.
我们提出了一种适用于铁磁固体的全温度磁振子形式理论。据我们所知，这是首次计算全温度自旋统计。到目前为止的普遍印象是，磁振子形式理论在居里点会失效，因为它引入了级数展开和非物理态。我们的处理方法基于对霍尔斯坦 - 普里马科夫变换的精确量子力学表示。为了实现这一目标，我们引入了“久保算符”。该处理方法适用于所有14种布拉菲晶格类型，而不限于简单立方晶胞。在本工作中，我们进行了零阶处理，涉及所有可能的自旋态，并排除所有非物理态。在后续论文中，我们将表明微扰后的能量值有很大不同，但磁性质与零阶结果相比仅发生了小的修正。
