Our paper on PRL shows a speed limit of spins, press release by Max Planck Institute for the Structure and Dynamics of Matter
Paper by Tao Yu*, Chen Wang, Michael Sentef, and Gerrit E. W. Bauer: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.137202
Please see press release at https://www.mpsd.mpg.de/536352/2021-03-yu-doppler?c=17189