Designing and characterizing the many-body behaviors of quantum materials represents a prominent challenge for understanding strongly correlated physics and quantum information processing. We constructed artificial quantum magnets on a surface by using spin-1/2 atoms in a scanning tunneling microscope (STM). These coupled spins feature strong quantum fluctuations due to antiferromagnetic exchange interactions between neighboring atoms. To characterize the resulting collective magnetic states and their energy levels, we performed electron spin resonance on individual atoms within each quantum magnet. This gives atomic-scale access to properties of the exotic quantum many-body states, such as a finite-size realization of a resonating valence bond state. The tunable atomic-scale magnetic field from the STM tip allows us to further characterize and engineer the quantum states. These results open a new avenue to designing and exploring quantum magnets at the atomic scale for applications in spintronics and quantum simulations.
Bibliographical noteFunding Information:
We thank Bruce Melior for expert technical assistance; J.L. Lado and J. Fernández-Rossier for helpful discussions. We gratefully acknowledge financial support from the Office of Naval Research. S.-H.P., Y.B., T.E., P.W. and A.J.H. acknowledge support from Institute for Basic Science (IBS-R027-D1). A.A. acknowledges support from the Engineering and Physical Sciences Research Council (EP/L011972/1 and EP/P000479/1), the QuantERA European Project SUMO, and the European Union’s Horizon 2020 research and innovation program under grant agreement No 863098 (SPRING).
© 2021, The Author(s).