Schmidt Kai P, Uhrig Götz S
Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, D-50937 Köln, Germany.
Phys Rev Lett. 2003 Jun 6;90(22):227204. doi: 10.1103/PhysRevLett.90.227204. Epub 2003 Jun 4.
The transition from dimerized to uniform phases is studied in terms of spectral weights for spin chains using continuous unitary transformations. The spectral weights in the S=1 channel are computed perturbatively around the limit of strong dimerization. We find that the spectral weight is concentrated mainly in the subspaces with a small number of elementary triplets (triplons), even for vanishing dimerization. So, besides spinons, triplons may be used as elementary excitations in spin chains. We conclude that there is no necessity to use fractional excitations in low-dimensional, undoped, or doped quantum antiferromagnets.
利用连续幺正变换，从自旋链的谱权重角度研究了从二聚化相到均匀相的转变。在强二聚化极限附近微扰计算了(S = 1)通道中的谱权重。我们发现，即使二聚化消失，谱权重也主要集中在具有少量基本三重态（三重子）的子空间中。因此，除了自旋子之外，三重子也可作为自旋链中的基本激发。我们得出结论，在低维、未掺杂或掺杂的量子反铁磁体中无需使用分数激发。
