Structural and magnetic properties of FeMnx chains (x=1-6) supported on Cu2 N/Cu (100)

Abstract

Heterogeneous atomic magnetic chains are built by atom manipulation on a Cu2N/Cu (100) substrate. Their magnetic properties are studied and rationalized by a combined scanning tunneling microscopy (STM) and density functional theory (DFT) work completed by model Hamiltonian studies. The chains are built using Fe and Mn atoms ontop of the Cu atoms along the N rows of the Cu2N surface. Here, we present results for FeMnx chains (x=1-6) emphasizing the evolution of the geometrical, electronic, and magnetic properties with chain size. By fitting our results to a Heisenberg Hamiltonian we have studied the exchange-coupling matrix elements J for different chains. For the shorter chains, x≤2, we have included spin-orbit effects in the DFT calculations, extracting the magnetic anisotropy energy. Our results are also fitted to a simple anisotropic spin Hamiltonian and we have extracted values for the longitudinal-anisotropy D and transversal-anisotropy E constants. These parameters together with the values for J allow us to compute the magnetic excitation energies of the system and to compare them with the experimental data. ; D.-J.C. acknowledges the European Union for support under the H2020-MSCA-IF-2014 Marie-Curie Individual Fellowship programme Proposal No. 654469 and a previous postdoctoral fellowhship from the Alexander von Humboldt foundation. D.-J.C. and S.L. acknowledge Edgar Weckert and Helmut Dosch (Deutsches Elektronen-Synchrotron, Hamburg, Germany) for providing high-stability laboratory space. N.L. acknowledges financial support from Spanish MINECO (Grant No. MAT2015-66888-C3-2-R). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant No. SEV-2013-0295). ; Peer Reviewed