Zero field stability of holmium single atom magnets

Since their magnetic remanence was first measured in 2016, holmium single atom magnets on MgO/Ag(100) have garnered significant attention due to their hour long spin lifetimes, read and write-ability with spin-polarized scanning tunneling microscopy (SP-STM), and high coercive magnetic field [1-3]. Despite having been characterized with X-Ray absorption, STM, and electron spin-resonance STM, the system has not been measured at zero field. This has led to ambiguities concerning the electronic ground state of Ho/MgO and the stability of the system at zero field [3]. Here we present SP-STM measurements demonstrating the zero-field stability of Ho single atom magnets. Using antiferromagnetic Mn₈₈Ni₁₂ tips, we read the atom’s magnetic state, allow it to evolve under zero field conditions, and read it again. We discuss how these measurements can be used to determine the electronic ground state of the system.

[1] F. Donati et al., Science 352, 318 (2016).
[2] F. D. Natterer et al., Nature 543, 226 (2017).
[3] F. D. Natterer et al., Phys Rev. Lett. 121, 027201 (2018).