A Scanning Tunneling Microscope (STM) is one of the most important scanning probe tools available to study and manipulate matter at the nanoscale. In a STM, a tip is scanned on top of a surface with a separation of a few \AA. Often, the tunneling current between tip and sample is maintained constant by modifying the distance between the tip apex and the surface through a feedback mechanism acting on a piezoelectric transducer. This produces very detailed images of the electronic properties of the surface. The feedback mechanism is nearly always made using a digital processing circuit separate from the user computer. Here we discuss another approach, using a computer and data acquisition through the USB port. We find that it allows succesful ultra low noise studies of surfaces at cryogenic temperatures. We show results on different compounds, a type II Weyl semimetal (WTe2), a quasi two-dimensional dichalcogenide superconductor (2H-NbSe2), a magnetic Weyl semimetal (Co3Sn2S2) and an iron pnictide superconductor (FeSe).
@article{arxiv.2204.13011,
title = {Simplified feedback control system for Scanning Tunneling Microscopy},
author = {Francisco Martín-Vega and Víctor Barrena and Raquel Sánchez-Barquilla and Marta Fernández-Lomana and José Benito Llorens and Beilun Wu and Antón Fente and David Perconte Duplain and Ignacio Horcas and Raquel López and Javier Blanco and Juan Antonio Higuera and Samuel Mañas-Valero and Na Hyun Jo and Juan Schmidt and Paul C. Canfield and Gabino Rubio-Bollinger and José Gabriel Rodrigo and Edwin Herrera and Isabel Guillamón and Hermann Suderow},
journal= {arXiv preprint arXiv:2204.13011},
year = {2022}
}