Millikelvin STM with Magnetic Cooling
We have recently developed an ultra-high vacuum scanning tunnelling microscope that reaches a base temperature of 0.03 Kelvin. It employs adiabatic demagnetisation refrigeration (ADR).
Although the lowest temperature achieved in our ADR STM is slightly higher than that of commercial 3He-4He dilution refrigerators used for UHV STM applications, our setup has several crucial advantages. First, its temperature regulation is easy, fast and precise. The second advantage, which is a direct consequence of the solid-state design of the ADR cryostat and the absence of circulating liquids, is its modularity. Finally, the third unique feature of our instrument is the custom-designed giant activated charcoal sorption pump that allows continuous operation of the bath cryostat’s 1K pot for more than two weeks in an environment that is completely free of mechanical vibrations.