Realization of a closed-cycle dilution refrigerator for nanoscale magnetometry

We present the implementation of a mechanical pump-free, dilution refrigerator with an automatic cool-down protocol. The cooling process utilizes a liquid nitrogen pre-cool circuit, a pulse tube cooler, and a custom internal dilution unit manufactured by Chase Cryogenics. The dilution unit employs charcoal sorption pumps and electronic heat switches to regulate the condensation and subsequent evaporative cooling of $^{3}$He, $^{4}$He, and a mash of both in three separate chambers. We achieve a base temperature of 85 mK with a 10-15 hour hold time. The unit presents a simple, compact, low vibration platform for conducting a wide spectrum of low temperature transport experiments. As an example, we present microwave frequency SQUID magnetometry data collected in this unit.