Microwave Microscope Studies of Trapped Vortex Dynamics in Superconductors

Abstract

Trapped vortices in superconductors introduce residual resistance in superconducting radio-frequency (SRF) cavities and disrupt the operation of superconducting quantum and digital electronic circuits. Understanding the detailed dynamics of trapped vortices under oscillating magnetic fields is essential for advancing these technologies. We have developed a near-field magnetic microwave microscope to study the dynamics of a limited number of trapped vortices under the probe when stimulated by a localized rf magnetic field. By measuring the local second-harmonic response ($P_{2f}$) at sub-femto-Watt levels, we isolate signals exclusively arising from trapped vortices, excluding contributions from surface defects and Meissner screening currents. Toy models of Niobium superconductor hosting vortex pinning sites are introduced and studied with Time-Dependent Ginzburg-Landau (TDGL) simulations of probe/sample interaction to better understand the measured second-harmonic response. The simulation results demonstrate that the second-harmonic response of trapped vortex motion under a localized rf magnetic field shares key features with the experimental data. This measurement technique provides access to vortex dynamics at the micron scale, such as depinning events and spatially-resolved pinning properties, as demonstrated in measurements on a Niobium film with an antidot flux pinning array.

References in corpus (15)

• Microwave response of vortices in superconducting thin films of Re and Al
• Ultra-high quality factors in superconducting niobium cavities in ambient magnetic fields up to 190 mG
• Trapping a single vortex and reducing quasiparticles in a superconducting resonator
• Dynamics of vortex penetration, jumpwise instabilities and nonlinear surface resistance of type-II superconductors in strong rf fields
• Nanometer-Scale Materials Contrast Imaging with a Near-Field Microwave Microscope
• Broadband dielectric microwave microscopy on $\mu$m length scales
• Doping-Dependent Nonlinear Meissner Effect and Spontaneous Currents in High-Tc Superconductors
• Near-Field Microwave Microscopy on nanometer length scales
• Imaging the Anisotropic Nonlinear Meissner Effect in Nodal YBa${}_2$Cu${}_3$O${}_{7-\delta }$ Thin-Film Superconductors
• Microwave Nonlinearities of an Isolated Long YBa_2Cu_3O_(7-d) Bi-crystal Grain Boundary
• High Frequency Nonlinear Response of Superconducting Cavity-Grade Nb surfaces
• Effect of random pinning on nonlinear dynamics and dissipation of a vortex driven by a strong microwave current
• Revealing the Microscopic Mechanism of Elementary Vortex Pinning in Superconductors
• Quantum thermodynamics with a single superconducting vortex
• Vortex dynamics induced by scanning SQUID susceptometry

Cited by in corpus (4)

• Structured light and induced vorticity in superconductors I: Linearly polarized light
• Superuniversal Statistics with Topological Origins for non-Hermitian Scattering Singularities
• Effect of charge-imbalance potential relaxation on the high-frequency vortex dynamics and kinetic inductance of superconducting circuits
• Microscopic Investigation of rf Vortex Nucleation in Nb3Sn Films Using a Near-Field Magnetic Microwave Microscope