Innovative ultra-low temperature thermometry guided by numerical simulations.

Ultra-low temperature (ULT) measurements below 1 mK present a difficult challenge, especially in the presence of high magnetic fields B. We are working on developing novel ULT thermometry in order to meet User demand at the NHMFL High B/T Facility. For example, specific heat and thermal transport experiments at ULT and high B - particularly on small crystals or nanostructures – are essential to studies of quantum criticality, superconductors with very low transition temperatures, or to provide evidence for a quantum spin liquid state. To enable rapid measurements of small samples, we are simultaneously working on optimization of existing thermometers and development of thermodynamic simulations to predict thermometer warmup curves without the need to wait for full thermalization. In addition, we can use these simulation techniques to guide more efficient experiment design. I will talk about the development and use of these simulations.