Holmium Single-Atom Magnets

Thermal and Magnetic-Field Stability of Holmium Single-Atom Magnets

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.

Abstract


We use spin-polarized scanning tunneling microscopy to demonstrate that Ho atoms on magnesium oxide exhibit 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. The transverse magnetic anisotropy energy is estimated from magnetic field and bias voltage dependent switching rates at 4.3 K. Our measurements constrain the possible ground state of Ho single-atom magnets to either Jz=7 or 8, both compatible with magnetic bistability at fields larger than 10 mT.
 
X