Samenvatting

Scanning tunneling microscopy is an important and enabling tool for condensed matter physics and surface science. The low temperature STM in Leiden (Prof. J. Van Ruitenbeek and Prof J. Aarts) is used for research in the field of atomic/molecular electronics and superconductivity. The current low temperature STM head can scan an area of 300 nm by 300 nm. Sometimes the scanned surface of the sample is not suited to perform a measurement: it can be locally too rough, or contaminated, or the STM probe (the “tip”) is just not within range of the region of interest. For this a coarse stage is needed that will move the sample to a new position to scan. Such a coarse stage was not implemented in the current STM.

The new design will have the same Z motor , because the current Z motor functions well and is compact (In this Z motor the Z coarse and fine stage are combined). The XY motor should not rotate or vibrate . The new XY motor will also house a new sample holder which will allow two separate currents through the sample, as this is required for future experiments.

The current motor is inspired by a well-established low temperature design by Pan et al, but was adapted to achieve a more compact and rigid microscope. The new design is also based on the Pan design, but the challenge is to adapt it again in order to make it very compact (because of the small space). All of this without compromising in rigidity and temperature stability.

In this work we discuss several concepts (see appendix C) with their advantages and disadvantages and we motivate the choice (for a particular and promising design see chapter 3). For two of the concepts resonance frequencies have been calculated with Comsol Multiphysics. Also for the most important design an electrodynamic calculation has been made.