Researchers at CEA/CNRS/Université Paris Saclay, University College London and ETH Zurich have recently devised a new method to control the temperature of a spin ensemble by increasing electron spin polarization above its thermal equilibrium value. Their research, featured in Nature Physics, builds on a study they conducted back in 2016.
Source:
https://phys.org/news/2020-05-technique-radiative-cooling-ensembles.html