Complex trend of magnetic order in Fe clusters on4dtransition-metal surfaces. I. Experimental evidence and Monte Carlo simulations

Abstract

We demonstrate the occurrence of compensated spin configurations in Fe clusters and monolayers on Ru(0001) and Rh(111) by a combination of x-ray magnetic circular dichroism experiments, first-principles calculations, and Monte Carlo simulations. Our results reveal complex intracluster exchange interactions which depend strongly on the substrate 4d-band filling, the cluster geometry, as well as lateral and vertical structural relaxations. The importance of substrate 4d-band filling manifests itself also in small nearest-neighbor exchange interactions in Fe dimers and in a nearly inverted trend of the Ruderman-Kittel-Kasuya-Yosida coupling constants for Fe adatoms on the Ru and Rh surface.

Complex trend of magnetic order in Fe clusters on4dtransition-metal surfaces. II. First-principles calculations

“…Experimental evidence of our findings is presented in Ref. [32]. Unexpectedly, many of the Fe clusters display a compensated antiferromagnetic or ferrimagnetic state.…”

Complex Magnetic Exchange Coupling between Co Nanostructures and Ni(111) across Epitaxial Graphene

“…Similarly to single atoms, Co atoms in dimers prefer to adsorb on adjacent fcc sites for U = 3 eV. Interestingly, we find a Co–Co AFM exchange interaction, which hints at compensated magnetic structures in Co dimers and small clusters, , suggesting that these contribute only marginally to the XMCD signal and that, at low coverage, mainly the magnetic moment of single Co atoms is probed …”

“…Interestingly, we find a Co−Co AFM exchange interaction, which hints at compensated magnetic structures in Co dimers and small clusters, 36,37 suggesting that these contribute only marginally to the XMCD signal and that, at low coverage, mainly the magnetic moment of single Co atoms is probed. 38 In the case of the Co ML, the preferred adsorption geometry corresponds to Co atoms on top sites, at a distance of 2.9 Å, from the G layer and with a spin moment m S ≃ 1.9 μ B . The magnetic exchange coupling between Co and Ni mediated by graphene is ferromagnetic and in the range of 30 meV/Coatom.…”

Interface formation for a ferromagnetic/antiferromagnetic bilayer system studied by scanning tunneling microscopy and first-principles theory

“…For example, many recent studies focused on the growth and properties of Fe on topological insulators, 4d transition-metal surfaces, wide band-gap semiconductors, and carbon-based materials such as C 60 and graphene. [1][2][3][4][5][6] Clearly of great importance to any material system is how the Fe grows and couples magnetically to it. This is of fundamental importance to the field of magnetic exchangebias systems [7,8] which are ubiquitous in modern magnetic recording technology, since the discovery of giant magneto-resistance.…”