Tjerk Oosterkamp1

1, Leiden University, Leiden, , Netherlands

Pulse tube refrigerators are becoming more common, because they are cost efficient and demand
less handling than conventional (wet) refrigerators. Also these cryostats provide a much larger experimental
space than conventional ones. This will be particularly useful for scanning probe microscopes which include
metrological functionalities.
However, a downside of a pulse tube system
is the vibration level at the cold-head, which is in most designs several micrometers. We implemented
vibration isolation techniques which significantly reduced vibration levels at the experiment.
These optimizations were necessary for the vibration sensitive magnetic resonance force microscopy
experiments at milli-kelvin temperatures for which the cryostat is intended. With these modifications
we show atomic resolution scanning tunneling microscopy.

A.M.J. den Haan, G.H.C.J. Wijts, F. Galli, O. Usenko, G.J.C. van Baarle, D.J. van der Zalm, T.H. Oosterkamp
Atomic resolution scanning tunneling microscopy in a cryogen free dilution refrigerator at 15 mK.
Rev. Sci. Instrum. 85 (2014) 035112.