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arXiv 2606.26014cond-mat.str-el
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Rashba-Hubbard链中的自旋调制——张量网络研究

Spin modulations in the Rashba-Hubbard chain -- a tensor network study

Institute of Physics, Slovak Academy of Sciences(斯洛伐克科学院物理研究所);National Yang Ming Chiao Tung University(国立阳明交通大学);National Center for Theoretical Sciences(国家理论科学中心);Center for Theoretical and Computational Physics, National Yang Ming Chiao Tung University(国立阳明交通大学理论与计算物理中心);Department of Physics and Center for Quantum Frontiers of Research and Technology (QFort), National Cheng Kung University(国立成功大学物理系暨量子前沿研究与技术中心(QFort))

Jozef Genzor, Roman Krčmár, Andrej Gendiar, Chia-Min Chung, Denis Kochan

AI总结:

利用DMRG研究一维Rashba-Hubbard链,发现均匀自旋轨道耦合可通过局域自旋旋转映射为普通Hubbard链,导致自旋结构因子出现侧带,而电荷性质仅受带宽重整化影响。

摘要:

在开放单带Hubbard链中,均匀自旋轨道耦合在哈密顿量层面是一个可精确移除的SU(2)规范场,但在实验室坐标系的自旋关联层面则不然。我们利用密度矩阵重整化群计算排斥性一维Rashba-Hubbard链来研究这种分离。对于开放边界条件,一个依赖于格点的自旋旋转将具有跃迁t和Rashba自旋轨道强度λ的模型映射到具有重整化跃迁t_λ=√(t^2+λ^2)的普通Hubbard链。因此,电荷和能量诊断仅通过带宽重整化受到影响,这在弱λ/t下是二次的。然而,自旋关联已经在线性阶响应,因为相同的变换通过波矢k_so=2arctan(λ/t)旋转局域自旋基。我们使用DMRG在有限开放链的填充图中验证了这一可观测的后果。填充结构遵循规范等价的Hubbard模型,而自旋结构因子显示出预测的自旋轨道边带。主导的Hubbard链磁波矢k_0被变换为k_0±k_so的分量,并折叠到开放链的布里渊区。在半填充时,其中k_0=π,两个边带折叠成一个单一的面内自旋螺旋波,具有k=π-k_so<π。在半填充之外,非公度的Hubbard自旋响应分裂成两个不同的自旋轨道移动分量,产生实空间拍频图案。我们的结果为一维自旋轨道耦合的可精确移除极限提供了填充分辨的张量网络基准,并为自旋轨道耦合无法再规范掉的情况(如梯子、多轨道链、环、邻近化导线和高维Hubbard系统)建立了可控的参考点。

英文摘要:

Uniform spin-orbit coupling in an open single-band Hubbard chain is an exactly removable \(SU(2)\) gauge field at the Hamiltonian level, but not at the level of laboratory-frame spin correlations. We study this separation using density matrix renormalization group calculations for the repulsive one-dimensional Rashba-Hubbard chain. For open boundary conditions, a site-dependent spin rotation maps the model with hopping \(t\) and Rashba spin-orbit strength \(λ\) onto the ordinary Hubbard chain with renormalized hopping \(t_λ=\sqrt{t^2+λ^2}\). Consequently, charge and energy diagnostics are affected only through the bandwidth renormalization, which is quadratic in weak \(λ/t\). Spin correlations, however, respond already at linear order because the same transformation rotates the local spin basis by the wave vector \(k_{\rm so}=2\arctan(λ/t)\). We use DMRG to verify this observable consequence across the filling diagram of finite open chains. The filling structure follows the gauge-equivalent Hubbard model, whereas the spin structure factor shows the predicted spin-orbit sidebands. A dominant Hubbard-chain magnetic wave vector \(k_0\) is transformed into components at \(k_0\pm k_{\rm so}\), folded into the open-chain Brillouin zone. At half filling, where \(k_0=π\), the two sidebands fold onto a single, in-plane, spin spiral wave with \(k=π-k_{\rm so}<π\). Away from half filling, the incommensurate Hubbard spin response splits into two distinct spin-orbit-shifted components, producing a real-space beating pattern. Our results provide a filling-resolved tensor-network benchmark for the exactly removable limit of one-dimensional spin-orbit coupling, and establish a controlled reference point for ladders, multiorbital chains, rings, proximitized wires, and higher-dimensional Hubbard systems where spin-orbit coupling can no longer be gauged away.

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