Tuning emergent magnetism in a Hund’s impurity A. A. Khajetoorians, 1,2, * M. Valentyuk, 3, 4 M. Steinbrecher, 1 T. Schlenk, 1 A. Shick, 5 J. Kolorenc, 5 A. I. Lichtenstein, 3 T. O. Wehling, 6 R. Wiesendanger, 1 and J. Wiebe 1, † 1 Institute of Applied Physics, Hamburg University, D-20355 Hamburg, Germany 2 Institute for Molecules and Materials (IMM), Radboud University, 6525 AJ Nijmegen, The Netherlands. 3 I. Institute of Theoretical Physics, Hamburg University, D-20355 Hamburg, Germany 4 Department of Theoretical Physics and Applied Mathematics, Ural Federal University, 620002 Ekaterinburg, Russia 5 Institute of Physics, ASCR, Na Slovance 2, CZ-18221 Prague, Czech Republic 6 Institute for Theoretical Physics, Bremen Center for Computational Material Science, University of Bremen, D-28359 Bremen, Germany Abstract The recently proposed theoretical concept of a Hund’s metal is regarded as a key to explain the exotic magnetic and electronic behavior occuring in the strongly correlated electron systems of multiorbital metallic materials. However, a tuning of the abundance of parameters, that determine these systems, is experimentally challenging. Here, we investigate the smallest possible realization of a Hund’s metal, a Hund’s impurity, realized by a single magnetic impurity strongly hybridized to a metallic substrate. We experimentally control all relevant parameters including magnetic anisotropy and hybridization by hydrogenation with the tip of a scanning tunneling microscope and thereby tune it through a regime from emergent magnetic moments into a multi-orbital Kondo state. Our comparison of the measured temperature and magnetic field dependent spectral functions to advanced many-body theories will give relevant input for their application to non-Fermi liquid transport, complex magnetic order, or unconventional superconductivity. 1 arXiv:1604.03854v1 [cond-mat.str-el] 13 Apr 2016