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. 2016 Dec 8:7:13646.
doi: 10.1038/ncomms13646.

Engineering the magnetic coupling and anisotropy at the molecule-magnetic surface interface in molecular spintronic devices

Victoria E Campbell  1 , Monica Tonelli  1 , Irene Cimatti  1 , Jean-Baptiste Moussy  2 , Ludovic Tortech  3 , Yannick J Dappe  2 , Eric Rivière  1 , Régis Guillot  1 , Sophie Delprat  4 , Richard Mattana  4 , Pierre Seneor  4 , Philippe Ohresser  5 , Fadi Choueikani  5 , Edwige Otero  5 , Florian Koprowiak  6 , Vijay Gopal Chilkuri  6 , Nicolas Suaud  6 , Nathalie Guihéry  6 , Anouk Galtayries  7 , Frederic Miserque  8 , Marie-Anne Arrio  9 , Philippe Sainctavit  5   9 , Talal Mallah  1
Affiliations

Engineering the magnetic coupling and anisotropy at the molecule-magnetic surface interface in molecular spintronic devices

Victoria E Campbell et al. Nat Commun. .

Abstract

A challenge in molecular spintronics is to control the magnetic coupling between magnetic molecules and magnetic electrodes to build efficient devices. Here we show that the nature of the magnetic ion of anchored metal complexes highly impacts the exchange coupling of the molecules with magnetic substrates. Surface anchoring alters the magnetic anisotropy of the cobalt(II)-containing complex (Co(Pyipa)2), and results in blocking of its magnetization due to the presence of a magnetic hysteresis loop. In contrast, no hysteresis loop is observed in the isostructural nickel(II)-containing complex (Ni(Pyipa)2). Through XMCD experiments and theoretical calculations we find that Co(Pyipa)2 is strongly ferromagnetically coupled to the surface, while Ni(Pyipa)2 is either not coupled or weakly antiferromagnetically coupled to the substrate. These results highlight the importance of the synergistic effect that the electronic structure of a metal ion and the organic ligands has on the exchange interaction and anisotropy occurring at the molecule-electrode interface.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. Synthesis of the complexes and surface deposition.
Schematic view of the formation of the metal ion containing complexes (M=Co and Ni) and their anchoring to the metal iron-oxide substrate by the formation of M-OPO-Fe bonds and the releasing of water molecules.
Figure 2
Figure 2. Complex Co- and Ni(Pyipa)2.
X-ray crystal structure of Co(Pyipa)2 (a) and Ni(Pyipa)2 (c); C, grey; N, lilac; O, red; P, orange; H, white; Co, blue; Ni, green. The red, green and blue axes represent the x, y, z direction of the anisotropy tensor, respectively. The magnetization as a function of field plots for Co(Pyipa)2 (b) and Ni(Pyipa)2 (d) solid lines correspond to the best fits; see SI for the parameter values.
Figure 3
Figure 3. Monolayer of Co(Pyipa)2 on epitaxial Fe3O4.
(a) Schematic representation of the DFT minimized orientation of Co(Pyipa)2 anchored onto epitaxial Fe3O4: C, grey; N, lilac; O, red or magenta when bound to a phosphonate; P, orange; H, white; Co, blue; Ni, green; Fe, gold or green when bound to the molecule; (b) AFM image of a monolayer of Co(Pyipa)2 anchored onto epitaxial Fe3O4; (c) Surface profile of the monolayer of Co(Pyipa)2.
Figure 4
Figure 4. XAS/XMCD spectra of a monolayer of Co- and Ni(Pyipa)2.
(a) Cobalt, and (b) Nickel L2,3 edges XAS (black and grey line) and XMCD (red lines) spectra recorded at T=2 K, and θ=45° using left (σ+) and right hand (σ−) circularly polarized light in 6.5 T field; (c) schematic representation of the measurement geometry.
Figure 5
Figure 5. Element-specific field dependence of the magnetization of the complexes and surface (Fe).
Hysteresis curves (multiplied by −1) of the Co atoms (blue), Ni atoms (green) and Fe atoms (grey) obtained at the L2,3 edges XMCD maxima at T=2 K, and θ=45°. (Monochromatized X-rays are set at the energy of the maximum absolute value of the XMCD signal (that is, hν=777.5 eV for Co, hν=851 eV for Ni, and hν=707 eV for Fe) then the external magnetic field is switched step by step from +6.5 T down to −6.5 T and back to +6.5 T. At each step the magnetic field is switched from left to right circular polarization to yield the element specific magnetization curves.
Figure 6
Figure 6. Geometry of the exchange interaction.
(a) Interaction topology between the MPyipa2 (M=Ni or Co) and the surface Fe ions. Optimized geometry of the singly occupied magnetic orbitals for Ni(Pyipa)2 (b) and Co(Pyipa)2 (c). Positive (red) and negative (green) isosurfaces for the high-spin solution. C, grey; N, lilac; O, red; P, orange; Co, blue; Ni, green; Fe, dark orange; hydrogen atoms were omitted for clarity. The MO labels are in ascending energy levels.
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References

    1. Bogani L. & Wernsdorfer W. Molecular spintronics using single-molecule magnets. Nat. Mater. 7, 179–186 (2008). - PubMed
    1. Sanvito S. Molecular spintronics. Chem. Soc. Rev. 40, 3336 (2011). - PubMed
    1. Barraud C. et al.. Unravelling the role of the interface for spin injection into organic semiconductors. Nat. Phys. 6, 615–620 (2010).
    1. Blouzon C., Ott F., Tortech L., Fichou D. & Moussy J. B. Anti-ferromagnetic coupling in hybrid magnetic tunnel junctions mediated by monomolecular layers of α-sexithiophene. Appl. Phys. Lett. 103, 042417 (2013).
    1. Wende H. et al.. Substrate-induced magnetic ordering and switching of iron porphyrin molecules. Nat. Mater. 6, 516–520 (2007). - PubMed

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