Downscaling of multiprobe STM experiments: towards atomic level understanding of transport phenomena

Multiprobe scanning tunneling microscopy (STM) based techniques allow determination of electronic and spin transport in variety of systems supported on surfaces of solid materials. Classical 2- and 4-probe methods are currently considered as universal tools for in-situ transport measurements on mesoscopic scales (typically hundreds of nanometers). Alternatively, application of scanning tunneling potentiometry (STP) visualizes potential change during such mesoscopic charge current transport with a nominal nanometer resolution. Here, on chosen examples we would like to discuss our efforts towards changing of this mesoscopic experimental paradigm by downscaling of 2-probe STM and STP experiments towards the atomic level. In this case the charge and spin current supplying probes are positioned in atomically defined locations with respect to the characterized nanosystem. In such configuration multiprobe techniques could directly visualize quantum nature of coherent carriers.