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arXiv 1705.04450cond-mat.str-el
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四链圆柱体受抑哈伯德模型的各向异性交叉

Anisotropy crossover in the frustrated Hubbard model on four-chain cylinders

G. Ehlers, B. Lenz, S. R. Manmana, R. M. Noack

摘要:

出于在层状有机$κ$盐的维度交叉,我们确定了一个系统的相图的四个周期性耦合哈伯德链与挫折在半填充作为一个函数的链间跳跃${t_{\perp}/t}$和相互作用强度${U/t}$在一个固定的挫折和链间跳跃${t'/t_{\perp}=-0.5}$的比例。我们覆盖的范围从一维极限的非耦合链(${t_{\perp}/t=0.0}$)的各向同性模型(${t_{\perp}/t=1.0}$)。对于强${U/t}$,我们发现一个反铁磁绝缘体,在弱到中等的相互作用制度,相图功能准一维反铁磁行为,一个无公度的自旋密度波,和金属相${t_{\perp}/t}$增加。我们通过它们的磁有序,介电响应,和占主导地位的静态相关性的相位。我们的分析主要是基于一个变种的密度矩阵重整化群算法的基础上,一个有效的混合实动量空间配方,在其中我们可以处理相对较大的晶格,虽然有限的宽度。这是补充的变分集群近似研究与集群几何对应的圆柱形晶格,使我们能够直接比较这两种方法的几何形状。作为展望,我们联系了全二维系统中的维交叉研究工作。

英文摘要:

Motivated by dimensional crossover in layered organic $κ$ salts, we determine the phase diagram of a system of four periodically coupled Hubbard chains with frustration at half filling as a function of the interchain hopping ${t_{\perp}/t}$ and interaction strength ${U/t}$ at a fixed ratio of frustration and interchain hopping ${t'/t_{\perp}=-0.5}$. We cover the range from the one-dimensional limit of uncoupled chains (${t_{\perp}/t=0.0}$) to the isotropic model (${t_{\perp}/t=1.0}$). For strong ${U/t}$, we find an antiferromagnetic insulator; in the weak-to-moderate-interaction regime, the phase diagram features quasi-one-dimensional antiferromagnetic behavior, an incommensurate spin-density wave, and a metallic phase as ${t_{\perp}/t}$ is increased. We characterize the phases through their magnetic ordering, dielectric response, and dominant static correlations. Our analysis is based primarily on a variant of the density-matrix renormalization-group algorithm based on an efficient hybrid-real-momentum-space formulation, in which we can treat relatively large lattices albeit of a limited width. This is complemented by a variational cluster approximation study with a cluster geometry corresponding to the cylindrical lattice allowing us to directly compare the two methods for this geometry. As an outlook, we make contact with work studying dimensional crossover in the full two-dimensional system.

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