Institut für Theoretische Festkörperphysik, IFW Dresden, Germany.
Phys Rev Lett. 2012 Aug 17;109(7):076401. doi: 10.1103/PhysRevLett.109.076401. Epub 2012 Aug 13.
We study the effects of opening the band gap on the double exchange ferromagnetism. Applying the density-matrix renormalization group method and an analytical expansion from the dimer limit to the one-dimensional double exchange model, we demonstrate for a relevant region of the exchange coupling that, in the weak dimerization regime, the Peierls gap opens in the fully spin-polarized conduction band without affecting its ferromagnetism, whereas in the strong dimerization regime, the ferromagnetism is destroyed, and the Mott gap opens instead, leading the system to the antiferromagnetic quasi-long-range order. An insulator version of double exchange ferromagnetism is thus established.
我们研究了打开能隙对双交换铁磁体的影响。应用密度矩阵重整化群方法和从二聚体极限到一维双交换模型的解析展开，我们在相关的交换耦合区域证明了，在弱二聚化的情况下，Peierls 能隙在完全自旋极化的导带中打开，而不会影响其铁磁性，而在强二聚化的情况下，铁磁性被破坏，而 Mott 能隙打开，导致系统进入反铁磁准长程有序。因此，建立了双交换铁磁体的绝缘版本。
