We report magnetic bistability in single Dy atoms on NaCl(100) thin films. Individual Dy atoms substituting Na at the surface of the NaCl layer are thermally stable up to at least 300 K, display 4f9 occupancy, out-of-plane easy magnetization axis, and long spin relaxation time T1 of about 10 s at 2.5 K; thereby they are the first single atom magnet on a thermally stable adsorption site. Dy atoms adsorbed onto the Cl and bridge sites display 4f10 occupancy. Dy on top-Cl exhibit magnetic hysteresis and a T1 of 550 s at 0.3 T and 2.5 K. The observed slow magnetic relaxation of Dy on both adsorption sites introduces NaCl as an effective platform for single atom magnets.
@article{arxiv.2603.25608,
title = {Single Atom Magnets on Thermally Stable Adsorption Sites: Dy on NaCl(100)},
author = {M. Pivetta and M. Blanco-Rey and S. Reynaud and R. Baltic and A. Rary-Zinque and S. Toda Cosi and F. Patthey and B. V. Sorokin and A. Singha and F. Donati and A. Barla and L. Persichetti and P. Gambardella and A. Arnau and F. Delgado and S. Rusponi and H. Brune},
journal= {arXiv preprint arXiv:2603.25608},
year = {2026}
}