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arXiv 2210.04577cond-mat.str-el
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基于广义位置算子的拓扑不变量及其在相互作用Rice-Mele模型中的应用

Topological invariants based on generalized position operators and application to the interacting Rice-Mele model

Armando A. Aligia

摘要:

我们讨论了不同的属性和能力的几个拓扑不变量的位置算子的基础上,以确定相变,并比较更准确的方法,如交叉的激发能级和跳跃的Berry阶段。不变量的形式为$\text{Im} \text{ln} \left\langle \exp \left[ i(2π/L)Σ_{j}x_{j} \left( m_{_{\uparrow }}\hat{n}_{j\uparrow } +m_{\downarrow }\hat{n}_{j\downarrow }\right) \right] \right\rangle $,其中$L$是系统的长度,$x_{j}$是位点$j$的位置,$\hat{n}_{jσ}$是位点$j$上自旋为$σ$的粒子数的算子。我们表明,$m_{σ}$应该是整数,并在某些情况下,幅度大于1,导致定义良好的期望值。对于相互作用的赖斯-梅勒模型(其中包含相互作用的苏-Schrieffer-Heeger和离子哈伯德模型作为具体情况),我们表明,三个不同的不变量提供互补信息,是必要的和足够的不变量的反演对称性保护的区域中构建的相图。我们还讨论了电荷和自旋泵的后果,以及伊辛自旋相互作用或交错磁场的影响。

英文摘要:

We discuss different properties and the ability of several topological invariants based on position operators to identify phase transitions, and compare with more accurate methods, like crossing of excited energy levels and jumps in Berry phases. The invariants have the form $\text{Im} \text{ln} \left\langle \exp \left[ i(2π/L)Σ_{j}x_{j} \left( m_{_{\uparrow }}\hat{n}_{j\uparrow } +m_{\downarrow }\hat{n}_{j\downarrow }\right) \right] \right\rangle $, where $L$ is the length of the system, $x_{j}$ the position of the site $j$, $\hat{n}_{jσ}$ the operator of the number of particles at site $j$ with spin $σ$. We show that $m_{σ}$ should be integers, and in some cases of magnitude larger than 1 to lead to well defined expectation values. For the interacting Rice-Mele model (which contains the interacting Su-Schrieffer-Heeger and the Ionic Hubbard model as specific cases), we show that three different invariants give complementary information and are necessary and sufficient to construct the phase diagrams in the regions where the invariants are protected by inversion symmetry. We also discuss the consequences for pumping of charge and spin, and the effect of an Ising spin-spin interaction or a staggered magnetic field.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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