论文标题
掺杂XXZ梯子的复杂相图：定位和配对
Complex Phase Diagram of Doped XXZ Ladder: Localization and Pairing
论文作者
论文摘要
不同的潜在旋转相关性如何通过掺杂的莫特绝缘子的核心问题来大大改变基态性质。两腿XXZ梯子提供了典型的自旋背景，可以通过甲壳偏置各向异性从远程Néel订单调整为短距离``旋转液体''，从而在有限掺杂时产生复杂的相图。通过密度矩阵重新归一化的组方法，我们表明，尽管电荷总是在Néel排序阶段进行自定位，但出现了第二个绝缘阶段，其中掺杂的孔被配对，但保持局部定位，而横向自旋旋转相关性则降低了一个短距离，以使其成为Néel阶的经典。只有当Néel秩序通过进一步降低各向异性而完全消失时，配对才真正以路德 - emery状态为特征。相反，在面内铁磁XXZ方案中完全不存在配对，从而发现了从néel有序相中的电荷自定位到旋转液相中的费米 - 天然气状态的直接过渡。简要讨论一致的物理图片。
How the ground state nature can be dramatically changed by the distinct underlying spin correlation is a central issue of doped Mott insulators. The two-leg XXZ ladder provides a prototypical spin background, which can be tuned from a long-range Néel order to a short-range ``spin liquid'' via the superexchange anisotropy, giving rise to a complex phase diagram at finite doping. By density matrix renormalization group method, we show that although the charge is always self-localized in the Néel ordered phase, a second insulating phase emerges, in which the doped holes become paired but remain localized while the transverse spin-spin correlation reduces to short-ranged one to make the Néel order classical. Only when the Néel order totally disappears by further reducing anisotropy, does the pairing become truly coherent as characterized by a Luther-Emery state. In sharp contrast, the pairing is totally absent in the in-plane ferromagnetic XXZ regime, where a direct transition from the charge self-localization in the Néel ordered phase to a Fermi-gas-like state in the spin liquid phase is found. A consistent physical picture is briefly discussed.
