Resumé / Abstract :

Dopants and impurities are crucial in shaping the ground-state of host materials : semiconducting technology is based on their ability to donate or trap electrons, and they can even be used to transform insulators into high temperature superconductors. Due to limited time resolution, most atomic scale studies of the latter materials focussed on the effect of dopants on the electronic properties averaged over time. To lift this limitation, I will first present how we implemented cryogenic circuitry operating in the MHz regime into our home-built scanning tunnelling microscope in order to gain access to time-dependent information, including shot-noise, at the atomic scale [1]. After discussing the details of the circuitry, I will show how it enabled us to detect remarkable charge dynamics at select atomic sites in the high temperature superconductor Bi2Sr2CaCu2O8+x [2]. Lastly, I will demonstrate how we can use these sites, as well as other individual atoms, to manipulate superconductiv ity.

[1] F. Massee et al., Rev. Sci. Instrum. 89, 093708 (2018)

[2] F. Massee et al., Nature Communications 10, 544 (2019)

Contact : equipe-seminaires-nano@fondation-nanosciences.fr