Nanoelectronic thermometry and refrigeration for sub-millikelvin temperatures

It has recently been shown that magnetic refrigeration can be deployed on-chip to cool nanoelectronic devices below the base temperature of a dilution refrigerator [1, 2, 3]. This technique has the potential to unlock microkelvin electron temperatures in nanoscale structures and devices. However, there are still significant challenges in thermometry and thermal isolation to be overcome. In this talk, we present our recent work to lower the operating temperature of Coulomb blockade thermometers to ≈300µK, and to improve the base electron temperature reachable by demagnetisation refrigeration of on-chip copper.
[1] Bradley et al., Sci. Rep. 7, 45566 (2017)
[2] Palma, Scheller et al., Appl. Phys. Lett. 111, 253101 (2017)
[3] Yurttagül, Sarsby et al., Phys. Rev. Appl. 12, 011005 (2019)