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arXiv 2602.13709cond-mat.mes-hall
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强磁无序二维陈绝缘体中的无序诱导拓扑相

Disorder-Induced Topological Phases in a Two-Dimensional Chern Insulator with Strong Magnetic Disorder

University of Hamburg(汉堡大学);The Hamburg Centre for Ultrafast Imaging(汉堡超快成像中心)

Devesh Vaish, Michael Potthoff

AI总结:

研究强磁无序对陈绝缘体拓扑相的影响,发现无序可驱动无清洁极限对应的拓扑相,并通过数值计算揭示由格林函数零点而非极点驱动的拓扑相变。

摘要:

与陈绝缘体耦合的局域磁矩中的强方向性无序产生了拓扑相,这些相无法连续连接到清洁极限,因此是真正的无序驱动。我们在自旋ful Qi-Wu-Zhang模型中展示了这一点,该模型是二维陈绝缘体与单位长度的无序经典自旋耦合。使用两种互补方法数值计算拓扑相图:扭曲边界条件和拓扑哈密顿量技术。我们的结果表明,强无序可以作为一种基本的拓扑机制,而不仅仅是微扰。对于强交换耦合,调节质量参数揭示了具有不同陈数$C$的相之间的转变。值得注意的是,这种转变是由无序平均格林函数的零点(而非极点)穿过化学势驱动的,并且在任何清洁系统中都没有类似物。我们进一步确定了一个具有$C=0$的强耦合相,该相在拓扑上仍然非平凡,其特征是在经典自旋构型流形上具有不同的陈数$C^{(\mathrm{S})} \neq 0$。该相也是无序驱动的,因为在清洁极限下$C^{(\mathrm{S})}=0$。

英文摘要:

Strong directional disorder in local magnetic moments coupled to a Chern insulator gives rise to topological phases that cannot be continuously connected to the clean limit and are therefore genuinely disorder-driven. We demonstrate this in a spinful Qi-Wu-Zhang model of a two-dimensional Chern insulator coupled to disordered classical spins of unit length. The topological phase diagram is computed numerically using two complementary approaches: twisted boundary conditions and the topological Hamiltonian technique. Our results show that strong disorder can act as a fundamental topological mechanism rather than merely a perturbation. For strong exchange coupling, tuning the mass parameter reveals a transition between phases with different Chern numbers $C$. Remarkably, this transition is driven by zeros, rather than poles, of the disorder-averaged Green's function crossing the chemical potential, and has no analogue in any clean system. We further identify a strong-coupling phase with $C = 0$ that is nonetheless topologically nontrivial, characterized by a distinct Chern number $C^{(\mathrm{S})} \neq 0$ over the manifold of classical spin configurations. This phase is also disorder-driven, as $C^{(\mathrm{S})} = 0$ in the clean limit.

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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