Stochastic Resonance Magnetic Force Microscopy: A Technique for Nanoscale Imaging of Vortex Dynamics

          @misc{ pirsa_PIRSA:16050039,
            doi = {10.48660/16050039},
            url = {https://pirsa.org/16050039},
            author = {Budakian, Raffi},
            keywords = {Condensed Matter},
            language = {en},
            title = {Stochastic Resonance Magnetic Force Microscopy: A Technique for Nanoscale Imaging of Vortex Dynamics},
            publisher = {Perimeter Institute},
            year = {2016},
            month = {may},
            note = {PIRSA:16050039 see, \url{https://pirsa.org}}
          }
          

Abstract

In this talk, I will describe a new technique—stochastic resonance magnetic force microscopy (SRMFM)—developed in my group for imaging the vortex dynamics in multiply connected superconducting devices. Unlike existing techniques, which directly image vortices, our technique relies on the mechanism of stochastic resonance to image the fluctuations between different vortex configurations. I will present data, taken using Josephson junction arrays and ring structures, that reveal striking geometric patterns which emerge when the energy of different vortex configurations become degenerate at well-defined positions of a magnetic tip that is scanned above the surface of the device. By analyzing the fluctuation rate as a function of temperature or external field, we obtain detailed information regarding the energy barriers connecting different vortex configurations, as well as energy scales associated with vortex-vortex interactions. The technique also provides a convenient means to manipulate vortices in multiply connected superconducting structures, which may prove useful in certain topological quantum-computing applications.