Atomic exchange bias control of individual quantum magnets

Variable magnetic fields are crucial for modern data storage and spintronic applications but scaling magnetic fields to match the dimensions of individual nanomagnets is challenging. Exchange bias fields arising from the orbital overlap of magnetic atoms have been proposed as mechanism for local control of individual quantum magnets. We demonstrate that exchange coupling with a magnetic atom on the tip of a scanning tunneling microscope can be used to tune the spin state mixing of few-atom nanomagnets and thus yields complete control over nanomagnetism at atomic dimensions.