Manipulating Magnetism in a Single Molecule

摘要

The size of magnetic objects that can be manipulated in con-densed-matter environments has decreased over the last 50 years, from bulk ferro-magnets to thin films, nanocrystals, clusters, and now to single atoms and molecules (1-7). The single-atom orsingle-molecule regime is especially interesting because magnetism arises in this case from very few unpaired electronic spins and is thus quantum mechanical in nature. This property opens new opportunities that range from basic quantum impurity studiesto quantum information and spmtronics applications (8), Molecular systems, in particular, provide a useful means for "packaging" quantum spin centers, because molecules are structurally and electronically very flexible (7), This is readily seen in the work of Zhao et al. (9) on page 1542 of this issue, They show that it is possible to tune the spin behavior of a magnetic cobalt ion trapped within a single molecule by pruning the ligands of the molecule with the tip of a scanning tunneling microscope (STM).