A fundamental step towards atomic- or molecular-scale spintronic devices has recently been made by demonstrating that the spin of an individual atom deposited on a surface1, or of a small paramagnetic molecule embedded in a nanojunction2, can be externally controlled. An appealing next step is the extension of such a capability to the field of information storage, by taking advantage of the magnetic bistability and rich quantum behaviour of single-molecule magnets3,4,5,6 (SMMs). Recently, a proof of concept that the magnetic memory effect is retained when SMMs are chemically anchored to a metallic surface7 was provided. However, control of the nanoscale organization of these complex systems is required for SMMs to be integrated into molecular spintronic devices8,9. Here we show that a preferential orientation of Fe4 complexes on a gold surface can be achieved by chemical tailoring. As a result, the most striking quantum feature of SMMs—their stepped hysteresis loop, which results from resonant quantum tunnelling of the magnetization5,6—can be clearly detected using synchrotron-based spectroscopic techniques. With the aid of multiple theoretical approaches, we relate the angular dependence of the quantum tunnelling resonances to the adsorption geometry, and demonstrate that molecules predominantly lie with their easy axes close to the surface normal. Our findings prove that the quantum spin dynamics can be observed in SMMs chemically grafted to surfaces, and offer a tool to reveal the organization of matter at the nanoscale.
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Loth, S. et al. Controlling the state of quantum spins with electric currents. Nature Phys. 6, 340–344 (2010)
Parks, J. J. et al. Mechanical control of spin states in spin-1 molecules and the underscreened Kondo effect. Science 328, 1370–1373 (2010)
Sessoli, R., Gatteschi, D., Caneschi, A. & Novak, M. A. Magnetic bistability in a metal-ion cluster. Nature 365, 141–143 (1993)
Gatteschi, D., Sessoli, R. & Villain, J. Molecular Nanomagnets (Oxford Univ. Press, 2006)
Friedman, J. R., Sarachik, M. P., Tejada, J. & Ziolo, R. Macroscopic measurement of resonant magnetization tunneling in high-spin molecules. Phys. Rev. Lett. 76, 3830–3833 (1996)
Thomas, L. et al. Macroscopic quantum tunnelling of magnetization in a single crystal of nanomagnets. Nature 383, 145–147 (1996)
Mannini, M. et al. Magnetic memory of a single-molecule quantum magnet wired to a gold surface. Nature Mater. 8, 194–197 (2009)
Bogani, L. & Wernsdorfer, W. Molecular spintronics using single-molecule magnets. Nature Mater. 7, 179–186 (2008)
Rocha, A. R. et al. Towards molecular spintronics. Nature Mater. 4, 335–339 (2005)
Heersche, H. B. et al. Electron transport through single Mn12 molecular magnets. Phys. Rev. Lett. 96, 206801 (2006)
Jo, M. H. et al. Signatures of molecular magnetism in single-molecule transport spectroscopy. Nano Lett. 6, 2014–2020 (2006)
Mannini, M. et al. XAS and XMCD investigation of Mn12 monolayers on gold. Chem. Eur. J. 14, 7530–7535 (2008)
Mannini, M. et al. X-ray magnetic circular dichroism picks out single-molecule magnets suitable for nanodevices. Adv. Mater. 21, 167–171 (2009)
Gregoli, L. et al. Magnetostructural correlations in tetrairon(III) single-molecule magnets. Chem. Eur. J. 15, 6456–6467 (2009)
Margheriti, L. et al. Thermal deposition of intact tetrairon(III) single-molecule magnets in high-vacuum conditions. Small 5, 1460–1466 (2009)
Zyazin, A. S. et al. Electric field controlled magnetic anisotropy in a single molecule. Nano Lett. 10, 3307–3311 (2010)
Pineider, F. et al. Deposition of intact tetrairon(III) single molecule magnet monolayers on gold: an STM, XPS, and ToF-SIMS investigation. J. Mater. Chem. 20, 187–194 (2010)
Nakajima, R., Stohr, J. & Idzerda, Y. U. Electron-yield saturation effects in L-edge X-ray magnetic circular dichroism spectra of Fe, Co, and Ni. Phys. Rev. B 59, 6421–6429 (1999)
Gambardella, P. et al. Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface. Nature Mater. 8, 189–193 (2009)
Van der Laan, G., Schofield, P. F., Cressey, G. & Henderson, C. M. B. Natural linear dichroism at the Fe 2p absorption edge of gillespite. Chem. Phys. Lett. 252, 272–276 (1996)
Tancini, E. et al. Slow magnetic relaxation from hard-axis metal ions in tetranuclear single-molecule magnets. Chem. Eur. J. 16, 10482–10493 (2010)
Juhin, A. et al. X-ray linear dichroism in cubic compounds: the case of Cr3+ in MgAl2O4 . Phys. Rev. B 78, 195103 (2008)
Barra, A. L. et al. The origin of transverse anisotropy in axially symmetric single molecule magnets. J. Am. Chem. Soc. 129, 10754–10762 (2007)
Misiorny, M., Weymann, I. & Barnas, J. Spin diode behavior in transport through single-molecule magnets. Europhys. Lett. 89, 18003 (2010)
Ziemelis, K. (1996) Mesoscopic tunnelling of magnetization. Milestone 22: Nature Milestones in Spin 〈http://www.nature.com/milestones/milespin/full/milespin22.html〉 (2008)
Letard, I. et al. Remnant magnetization of Fe8 high-spin molecules: X-ray magnetic circular dichroism at 300 mK. J. Appl. Phys. 101, 113920 (2007)
VandeVondele, J. et al. Quickstep: fast and accurate density functional calculations using a mixed Gaussian and plane waves approach. Comput. Phys. Comm. 167, 103–128 (2005)
Bencini, A., Rajaraman, G., Totti, F. & Tusa, M. Modeling thiols on Au(111): structural, thermodynamic, and magnetic properties of simple thiols and thiol-radicals. Superlattices Microstruct. 46, 4–9 (2009)
Brouder, C. Angular dependence of X-ray absorption spectra. J. Phys. Condens. Matter 2, 701–738 (1990)
We acknowledge D. Gatteschi and J. Villain for discussions. F. Scheurer, J. P. Kappler, B. Muller, F. Nolting and N. Brookes are acknowledged for their contribution to the development of the synchrotron experimental set-ups used in this work. This work is based on experiments performed at the Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland, and the European Synchrotron Radiation Facility, Grenoble, France. The research leading to these results received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 226716, through the projects MolSpinQIP (FP7-ICT-2007-C-211284) and ERANET ‘NanoSci-ERA: Nanoscience in European Research Area’, from the Italian CNR, through the Commessa PM.P05.012, from the Italian MIUR, through the project PRIN 2008, and from Ente CRF. DFT calculations were carried out within the DEISA Extreme Computing Initiative projects AMNOS and QUNA.
The authors declare no competing financial interests.
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Mannini, M., Pineider, F., Danieli, C. et al. Quantum tunnelling of the magnetization in a monolayer of oriented single-molecule magnets. Nature 468, 417–421 (2010). https://doi.org/10.1038/nature09478
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