Large effect of metal substrate on magnetic anisotropy of Co on hexagonal boron nitride

We combine x-ray absorption spectroscopy (XAS), x-raymagnetic circular dichroism (XMCD) and x-ray magnetic linear dichroism (XMLD) data with first principles density functional theory (DFT) calculations and amultiorbital many-body Hamiltonian approach to understand the electronic and magnetic properties of Co atoms adsorbed on h-BN/Ru(0001) and h-BN/Ir(111). The XAS line shape reveals, for both substrates, an electronic configuration close to 3d(8), corresponding to a spin S = 1 Magnetic field dependent XMCD data show large (14 meV) out-of-plane anisotropy on h-BN/Ru(0001), while it is almost isotropic (tens of mu eV) on h-BN/Ir(111). XMLD data together with both DFT calculations and the results of the multiorbital Hubbard model suggest that the dissimilar magnetic anisotropy originates from different Co adsorption sites, namely atop Non h-BN/Ru(0001) and 6-fold hollow on h-BN/Ir(111).IG and AA acknowledge financial support by the Spanish Ministerio de Economia y Competitividad (MINECO Grant No. FIS2016-75862-P). The calculations were performed using the Computer Center at the Donostia International Physics Center (DIPC). FD acknowledges funding from the Ministerio de Ciencia e Innovacion, grant MAT2015-66888-C3-2-R and FEDER funds; Basque Government, grant IT986-16, and Canary Islands program Viera y Clavijo (Ref. 2017/0000231). We gratefully acknowledge funding by the Swiss National Science Foundation (SNSF) through Grants No. 200021_146715/1 (RB), No. 200020_157081/1 (AS), and No. PZ00P2_142474 (CW and JD)