Molecules 2018, 23(4), 964; https://doi.org/10.3390/molecules23040964
Magnetic Properties of Metal–Organic Coordination Networks Based on 3d Transition Metal Atoms
María Blanco-Rey 1,2, Ane Sarasola 2,3, Corneliu Nistor 4, Luca Persichetti 4, Christian Stamm 4, Cinthia Piamonteze 5, Pietro Gambardella 4, Sebastian Stepanow 4
, Mikhail M. Otrokov 2,6,7,8, Vitaly N. Golovach 1,2,6,9 and Andres Arnau 1,2,6,*
, Mikhail M. Otrokov 2,6,7,8, Vitaly N. Golovach 1,2,6,9 and Andres Arnau 1,2,6,*
1
Departamento de Física de Materiales UPV/EHU, 20018 Donostia-San Sebastián, Spain
2
Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
3
Departamento Física Aplicada I, Universidad del País Vasco, 20018 Donostia-San Sebastián, Spain
4
Department of Materials, ETH Zürich, Hönggerbergring 64, 8093 Zürich, Switzerland
5
Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
6
Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Basque Country, Spain
7
Tomsk State University, Tomsk 634050, Russia
8
Saint Petersburg State University, Saint Petersburg 198504, Russia
9
IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
*
Author to whom correspondence should be addressed.
Received: 21 February 2018 / Revised: 11 April 2018 / Accepted: 16 April 2018 / Published: 20 April 2018
(This article belongs to the Special Issue Electronic Structure Calculations Applied to Magnetic Phenomena)
Abstract
The magnetic anisotropy and exchange coupling between spins localized at the positions of 3d transition metal atoms forming two-dimensional metal–organic coordination networks (MOCNs) grown on a Au(111) metal surface are studied. In particular, we consider MOCNs made of Ni or Mn metal centers linked by 7,7,8,8-tetracyanoquinodimethane (TCNQ) organic ligands, which form rectangular networks with 1:1 stoichiometry. Based on the analysis of X-ray magnetic circular dichroism (XMCD) data taken at T = 2.5 K, we find that Ni atoms in the Ni–TCNQ MOCNs are coupled ferromagnetically and do not show any significant magnetic anisotropy, while Mn atoms in the Mn–TCNQ MOCNs are coupled antiferromagnetically and do show a weak magnetic anisotropy with in-plane magnetization. We explain these observations using both a model Hamiltonian based on mean-field Weiss theory and density functional theory calculations that include spin–orbit coupling. Our main conclusion is that the antiferromagnetic coupling between Mn spins and the in-plane magnetization of the Mn spins can be explained by neglecting effects due to the presence of the Au(111) surface, while for Ni–TCNQ the metal surface plays a role in determining the absence of magnetic anisotropy in the system. View Full-TextKeywords:
magnetism; metal–organic network; X-ray magnetic circular dichroism (XMCD); density functional theory
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Blanco-Rey, M.; Sarasola, A.; Nistor, C.; Persichetti, L.; Stamm, C.; Piamonteze, C.; Gambardella, P.; Stepanow, S.; Otrokov, M.M.; Golovach, V.N.; Arnau, A. Magnetic Properties of Metal–Organic Coordination Networks Based on 3d Transition Metal Atoms. Molecules 2018, 23, 964.
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