Ultimate control over magnetic properties of nano-scale surface structures has been one of the holy grails of the surface-science community for quite some time. Among the many ways of achieving this control I would like to highlight a few pertaining to metallic and semi-insulating surfaces.

For metallic surfaces I shall concentrate of the possibility to control surface magnetism with charge doping and external electric field (EEF) application, showing that (i) magneto-electric coupling via EEF-based charge manipulation is a way to tailor single adatom spins, exchange interaction between adsorbates or anisotropies of chains and layered systems [1-3]; (ii) the effect of EEF can be enhanced by immersing the target system into an electrolyte or ionic liquid [1,4] and (iii) that similar physics can be found in charge traps, metallic systems decoupled from a bulk electron bath. [1,5]

As powerful tools often turn out to have their drawbacks and side effects, also the use of substrate electrons' manipulation for tailoring magnetism at the nanoscale often unfavorably affect the dynamics and non-ground-state properties of nanostructures due to the electron scattering from the substrate's vast electron bath.

I would argue, that a compromise can be found in the use of semi-insulating substrates, such as thin layers of CuN, MgO of BN on a metallic support. As an example I shall show that (i) electric field can also be used on such surfaces to tailor the exchange-coupling of magnetic adatoms on MgO/Ag(001) and that (ii) control over the nanostructure-substrate coupling in conjunction with hydrogenation opens up a possibility to tune the spins of single Co adatoms on corrugated hexagonal boron nitride supported on Rh(111) [6]

[1] O. Brovko, P. Ruiz-Di­az, T.R. Dasa, and V.S. Stepanyuk, J. Phys. Cond. Matter 26, 093001 (2014)
[2] N. Negulyaev, V.S. Stepanyuk, W. Hergert, and J. Kirschner, Phys. Rev. Lett. 106, 037202 (2011)
[3] T.R. Dasa, P.A. Ignatiev, and V.S. Stepanyuk, Phys. Rev. B 85, 205447 (2012)
[4] L. Juarez-Reyes, G.M. Pastor, and V.S. Stepanyuk, Phys. Rev. B 86, 235436 (2012)
[5] P. Ruiz-Di­az, T.R. Dasa, and V. S. Stepanyuk, Phys. Rev. Lett. 110, 267203 (2013)
[6] P. Jacobson, T. Herden, M. Muenks, G. Laskin, O. Brovko, V. Stepanyuk, M. Ternes, and K. Kern, Nature Commun. 6, 8536 (2015)