论文标题
重新审视小$ u $的哈伯德梯子
Hubbard ladders at small $U$ revisited
论文作者
论文摘要
我们在分析和使用密度 - 矩阵重质化组（DMRG）的小$ U $限制中重新检查了两腿哈伯德梯子的零温度相图。我们发现了一个无处不在的路德 - emery阶段，但具有特征性的相互作用强度的行为，$ u^\ star $; for $U \gtrsim U^\star$, there is a single emergent correlation length $\log[ξ] \sim 1/U$, characterizing the gapped modes of the system, but for $U\lesssim U^\star$ there is a hierarchy of length scales, differing parametrically in powers of $U$, reflecting a two-step renormalization group flow to the ultimate fixed point.最后，为了说明此处开发的方法的多功能性，我们概述了它对圆柱体上半填充三角形晶格哈伯德模型的含义，并发现与有关同一问题的DMRG研究中有关小$ U $相的推论发生了冲突的结果。
We re-examine the zero temperature phase diagram of the two-leg Hubbard ladder in the small $U$ limit, both analytically and using density-matrix renormalization group (DMRG). We find a ubiquitous Luther-Emery phase, but with a crossover in behavior at a characteristic interaction strength, $U^\star$; for $U \gtrsim U^\star$, there is a single emergent correlation length $\log[ξ] \sim 1/U$, characterizing the gapped modes of the system, but for $U\lesssim U^\star$ there is a hierarchy of length scales, differing parametrically in powers of $U$, reflecting a two-step renormalization group flow to the ultimate fixed point. Finally, to illustrate the versatility of the approach developed here, we sketch its implications for a half-filled triangular lattice Hubbard model on a cylinder, and find results in conflict with inferences concerning the small $U$ phase from recent DMRG studies of the same problem.
