Yildiz Taylan, Tanatar B
Department of Physics, Bilkent University, 06800, Ankara, Türkiye.
Sci Rep. 2025 Oct 24;15(1):37307. doi: 10.1038/s41598-025-21294-x.
We investigate localization and persistent currents in a helical tight-binding lattice subject to two independent magnetic fluxes and a quasiperiodic on-site potential. Working with non-interacting, spinless fermions under periodic boundary conditions, we solve the model by exact diagonalization and study localization with both inverse and normalized participation ratios. We identify boundaries separating extended, mixed, and localized regimes by constructing a diagram incorporating potential strength and inter-ring coupling. In the metallic regime, persistent currents flowing around both the toroidal and poloidal directions show oscillations whose amplitude decays as disorder grows and vanishes past the localization threshold; in the localized regime, currents become flux-insensitive. We demonstrate that tuning magnetic fluxes, hopping strengths, or quasiperiodic potential amplitudes provides control over the critical disorder threshold. Our results suggest a versatile platform for disorder-and flux-controlled switching between conductive and insulating states.
我们研究了在一个受到两个独立磁通量和一个准周期在位势作用的螺旋紧束缚晶格中的局域化和持续电流。在周期性边界条件下处理无相互作用的无自旋费米子，我们通过精确对角化求解该模型，并使用逆参与率和归一化参与率来研究局域化。我们通过构建一个包含势强度和环间耦合的图表，确定了分隔扩展、混合和局域区域的边界。在金属区域，沿环向和极向流动的持续电流表现出振荡，其振幅随着无序度的增加而衰减，并在超过局域化阈值时消失；在局域区域，电流变得对磁通量不敏感。我们证明，调节磁通量、跳跃强度或准周期势振幅可以控制临界无序阈值。我们的结果表明了一个用于在导电和绝缘状态之间进行无序和磁通量控制切换的通用平台。
