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arXiv · 2304.13093

Vortex dynamics induced by scanning SQUID susceptometry

Logan Bishop-Van Horn·Eli Mueller·Kathryn A. Moler
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Abstract

We measured the local magnetic response of a niobium thin film by applying a millitesla-scale AC magnetic field using a micron-scale field coil and detecting the response with a micron-scale pickup loop in a scanning superconducting quantum interference device (SQUID) susceptometry measurement. Near the film's critical temperature, we observed a step-like nonlinear and dissipative magnetic response due to the dynamics of a small number of vortex-antivortex pairs induced in the film by the local applied AC field. We modeled the dynamics of the measurement using a combined two-dimensional London-Maxwell and time-dependent Ginzburg-Landau approach, allowing us to construct a detailed real-space picture of the vortex motion causing the observed dissipative response. This work pushes scanning SQUID susceptometry of two-dimensional superconductors beyond the regime of linear response and lays the foundation for microscopic studies of vortex dynamics and pinning in superconducting devices and more exotic materials systems.

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Logan Bishop-Van Horn, Eli Mueller, Kathryn A. Moler. 2023-04-25. Vortex dynamics induced by scanning SQUID susceptometry. https://doi.org/10.1103/physrevb.107.224509

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