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arXiv · 2407.08547

Necklace-like pattern of vortex bound states

Zhiyong Hou·Kailun Chen·Wenshan Hong·Da Wang·Wen Duan·Huan Yang·Shiliang Li·Huiqian Luo·Qiang-Hua Wang·Tao Xiang·Hai-Hu Wen
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Abstract

Vortex is a topological defect in the superconducting condensate when a magnetic field is applied to a type-II superconductor, as elucidated by the Ginzburg-Landau theory. Due to the confinement of the quasiparticles by a vortex, it exhibits a circular shaped pattern of bound states with discrete energy levels, as predicted by the Caroli-de Gennes-Matricon theory in 1964. Here, however, we report a completely new type of vortex pattern which is necklace-like in an iron-based superconductor KCa2Fe4As4F2. Our theoretical analysis shows that this necklace-like vortex pattern arises from selective off-shell interference between vortex bound states of opposite angular momenta in the presence of rotational symmetry breaking due to disorders. This fascinating effect can be observed in a system with a small Fermi energy and wave vector, conditions fortuitously met in our samples. Our results not only disclose a novel vortex structure but also provide insights into comprehending the physics of the superconducting condensate.

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Zhiyong Hou, Kailun Chen, Wenshan Hong, Da Wang, Wen Duan, Huan Yang, Shiliang Li, Huiqian Luo, Qiang-Hua Wang, Tao Xiang, Hai-Hu Wen. 2024-07-11. Necklace-like pattern of vortex bound states. https://doi.org/10.1103/physrevx.15.011027

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