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Seminar MCBT: Friday, 6th October 2023 at 11:00 am


Francis Bettsworth (Lancaster University)


Title: On-chip magnetic refrigeration and thermal transport in nanoelectronic devices


Institut Néel, Room E424 (Salle Louis Weil)
Abstract: On-chip demagnetization refrigeration has recently emerged as a powerful tool for reaching microkelvin electron temperatures in nanoscale structures, with measured electron temperatures as low as 230 microkelvin. The technique integrates refrigeration with the circuitry of a device providing a more direct thermalisation route than traditional bulk nuclear demagnetisation, where device electrons and refrigerant are commonly connected by resistive thermal links. On-chip cooling has until recently been studied in conjunction with other off-chip refrigeration techniques, leaving many unanswered questions about the thermal subsystem dynamics and specific cooling potential of on-chip refrigerant alone.
This work studies a Coulomb blockade thermometer with integrated on-chip copper refrigerant both experimentally and numerically, showing that dynamics in this device are well-captured by a first-principles model. This study shows how to simulate thermal dynamics in devices down to microkelvin temperatures and outlines a recipe for a low-investment platform for quantum technologies and fundamental nanoscience in this novel electronic temperature range.