Spectroscopy of novel quantum states – Low temperature scanning tunneling microscope 4K

This equipment was commissioned in 2024. It is equipped with an Omicron LT AFM/STM microscope coupled under ultra-high vacuum to a preparation chamber with an ion gun, multiple evaporators (effusion cells, electron bombardment evaporators), a 1000K resistive heater and direct current heating, as well as a LEED/Auger.

This equipment allows the study of samples prepared in situ or simply cleaved under UHV down to the temperature of liquid helium, 4.2K. Its stability allows to produce high-resolution topographic images at the atomic scale. These images can be treated by Fourier transform analysis, which provides access to the electronic structure resolved in k. For example, we have used the LT STM to determine the effective doping of MISFIT Van Der Waals structures, or to observe charge density waves (CDW) in epitaxial transition metal dichalcogenides (TMDs) monolayers.

 The upcoming upgrade of this equipment will increase its autonomy at low temperatures and lower the electronic temperature of the tunnel junction to perform spectroscopic measurements on high Tc superconducting samples.