Magnetic remanence in single atoms

TLDR

Metal atoms adsorbed on surfaces can develop strong magnetization in an applied field, a phenomenon explored in molecular magnetism. The study aims to create a permanent magnet from a single atom. The atom avoids spin relaxation through quantum‑state symmetry and the oxide film blocking tunneling to the metal substrate. Single holmium atoms on MgO/Ag exhibit residual magnetism up to 30 K and bistability lasting 1500 s at 10 K. Published in Science, issue p.

Abstract

Stable magnets from single atoms An important goal in molecular magnetism is to create a permanent magnet from a single atom. Metal atoms adsorbed on surfaces can develop strong magnetization in an applied field (paramagnetism). Donati et al. show that single holmium atoms adsorbed on a magnesium oxide film grown on a silver substrate show residual magnetism for temperatures up to 30 K and bistabilty that lasts for 1500 s at 10 K (see the Perspective by Khajetoorians and Heinrich). The atom avoids spin relaxation by a combination of quantum-state symmetry and by the oxide film preventing the spin from interacting with the underlying metal via tunneling. Science , this issue p. 318 ; see also p. 296