Description

We use spin-polarized scanning tunneling microscopy to establish new boundaries for the temperature and field dependent magnetic stability of Ho single atom magnets on magnesium oxide. We demonstrated a coercive field of more than 8 T and magnetic bistability for many minutes, both at 35 K. The first spontaneous magnetization reversal events are recorded at 45 K, for which the metastable state relaxes in an external field of 8 T. Our measurements provide additional information on the ground state of Ho atoms and represent a further step toward understanding the intriguing behavior of single-atom magnets.