Freek Massee
     Laboratoire de Physique des Solides, CNRS

Shot-noise scanning tunneling microscopy


F. Massee et al., Nature Communications 10, 544 (2019)
Noisy defects in the high-Tc superconductor Bi2Sr2CaCu2O8+x

F. Massee et al., Review of Scientific Instruments 89, 093708 (2018)
Atomic scale shot-noise using cryogenic MHz circuitry

shot-noise compatible STM headShot-noise compatible STM head.
In a tunnel junction, the power of the current fluctuations, SI, is linear with the tunneling current, where the current noise is called shot-noise (SN). In a non-interacting system, the shot-noise is Poissonian as each electron crossing the tunnel barrier is independent from the others. As soon as the electrons in one of the terminals (i.e. the tip or the sample in the case of STM) are interacting with one another, the shot-noise will be directly affected. In addition to addressing dynamics, shot-noise also allows for directly measuring the charge locally as the shot-noise power spectrum is proportional to the charge transferred. At the Laboratoire de Physique des Solides in Orsay I have developed, together with experts in cryogenic, high frequency, low noise amplification at C2N, cryogenic circuitry operating in the MHz regime that allows my home-built scanning tunnelling microscope to measure shot noise at the atomic scale in correlated electron systems. The technical details of the setup and circuitry can be found here. For more details on 'traditional' scanning tunneling microscopy click here.