Design of a milliKelvin scanning probe microscope for both tunneling and force spectroscopy

We have designed and constructed a novel scanning probe microscope capable of both scanning tunneling microscopy (STM) and pendulum atomic force microscopy (pAFM) using conventional silicon cantilevers with a sensitive optical interferometry detection scheme. This instrument is designed to image nanoscale fluctuation-dissipation dynamics by measuring local changes in resonance frequency and quality factor of a vertically-oriented micro-cantilever oscillating like a pendulum above the sample. To achieve ultra-low electron temperatures, we introduce an efficient and scalable new method of fabricating powder filters with bendable PCBs. We demonstrate imaging at temperatures below 100 mK and magnetic fields up to 14 Tesla.