Magnetic materials interfaced with superconductors may reveal new physical phenomena with potential for quantum technologies. The use of molecules as magnetic components has already shown great promise, but the diversity of properties offered by the molecular realm remains largely unexplored. Here we investigate a submonolayer of tetrairon(iii) propeller-shaped single molecule magnets deposited on a superconducting lead surface. This material combination reveals a strong influence of the superconductor on the spin dynamics of the single molecule magnet. It is shown that the superconducting transition to the condensate state switches the single molecule magnet from a blocked magnetization state to a resonant quantum tunnelling regime. Our results open perspectives to control single molecule magnetism via superconductors and to use single molecule magnets as local probes of the superconducting state.
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The code to compute magnetic hysteresis using the kinetic Monte Carlo method is available from the ETH Zurich Data Archive, https://doi.org/10.3929/ethz-b-000393264.
Linder, J. & Robinson, J. W. A. Superconducting spintronics. Nat. Phys. 11, 307–315 (2015).
Franke, K. J., Schulze, G. & Pascual, J. I. Competition of superconducting phenomena and Kondo screening at the nanoscale. Science 332, 940–944 (2011).
Malavolti, L. et al. Tunable spin–superconductor coupling of spin ½ vanadyl-phthalocyanine molecules. Nano Lett. 18, 7955–7961 (2018).
Heinrich, B. W., Pascual, J. I. & Franke, K. J. Single magnetic adsorbates on s-wave superconductors. Prog. Surf. Sci. 93, 1–19 (2018).
Kezilebieke, S., Dvorak, M., Ojanen, T. & Liljeroth, P. Coupled Yu–Shiba–Rusinov states in molecular dimers on NbSe2. Nano Lett. 18, 2311–2315 (2018).
Farinacci, L. et al. Tuning the coupling of an individual magnetic impurity to a superconductor: quantum phase transition and transport. Phys. Rev. Lett. 121, 196803 (2018).
Heinrich, B. W., Braun, L., Pascual, J. I. & Franke, K. J. Protection of excited spin states by a superconducting energy gap. Nat. Phys. 9, 765–768 (2013).
Gatteschi, D., Sessoli, R. & Villain, J. Molecular Nanomagnets (Oxford Univ. Press, 2006).
Sanvito, S. et al. Molecular spintronics. Chem. Soc. Rev. 40, 3336–3355 (2011).
Godfrin, C. et al. Operating quantum states in single magnetic molecules: implementation of Grover’s quantum algorithm. Phys. Rev. Lett. 119, 187702 (2017).
Cornia, A., Mannini, M., Sessoli, R. & Gatteschi, D. Propeller-shaped Fe4 and Fe3M molecular nanomagnets: a journey from crystals to addressable single molecules. Eur. J. Inorg. Chem. 2019, 552–568 (2019).
Mannini, M. et al. Magnetic memory of a single-molecule quantum magnet wired to a gold surface. Nat. Mater. 8, 194–197 (2009).
Mannini, M. et al. Quantum tunnelling of the magnetization in a monolayer of oriented single-molecule magnets. Nature 468, 417–421 (2010).
Malavolti, L. et al. Magnetic bistability in a submonolayer of sublimated Fe4 single-molecule magnets. Nano Lett. 15, 535–541 (2015).
Totaro, P. et al. Tetrairon(iii) single-molecule magnet monolayers on gold: insights from ToF-SIMS and isotopic labeling. Langmuir 30, 8645–8649 (2014).
Margheriti, L. et al. X-ray detected magnetic hysteresis of thermally evaporated terbium double-decker oriented films. Adv. Mater. 22, 5488–5493 (2010).
Serrano, G. et al. Magnetic bistability of TbPc2 submonolayer on a graphene/SiC(0001) conductive electrode. Nanoscale 10, 2715–2720 (2018).
Wäckerlin, C. et al. Giant hysteresis of single-molecule magnets adsorbed on a nonmagnetic insulator. Adv. Mater. 28, 5195–5199 (2016).
Studniarek, M. et al. Understanding the superior stability of single‐molecule magnets on an oxide film. Adv. Sci. 6, 1901736 (2019).
Carretta, S. et al. Intra- and inter-multiplet magnetic excitations in a tetrairon(iii) molecular cluster. Phys. Rev. B 70, 214403 (2004).
Erler, P. et al. Highly ordered surface self-assembly of Fe4 single molecule magnets. Nano Lett. 15, 4546–4552 (2015).
Gragnaniello, L. et al. Uniaxial 2D superlattice of Fe4 molecular magnets on graphene. Nano Lett. 17, 7177–7182 (2017).
Paschke, F., Erler, P., Enenkel, V., Gragnaniello, L. & Fonin, M. Bulk-like magnetic signature of individual Fe4H molecular magnets on graphene. ACS Nano 13, 780–785 (2019).
Chanin, G. & Torre, J. P. Critical-field curve of superconducting lead. Phys. Rev. B 5, 4357–4364 (1972).
Rajaraman, G., Caneschi, A., Gatteschi, D. & Totti, F. A periodic mixed gaussians–plane waves DFT study on simple thiols on Au(111): adsorbate species, surface reconstruction, and thiols functionalization. Phys. Chem. Chem. Phys. 13, 3886–3895 (2011).
Ninova, S. et al. Valence electronic structure of sublimated Fe4 single-molecule magnets: an experimental and theoretical characterization. J. Mater. Chem. C 2, 9599–9608 (2014).
Kappler, J.-P. et al. Ultralow-temperature device dedicated to soft X-ray magnetic circular dichroism experiments. J. Synchrotron Rad. 25, 1727–1735 (2018).
Mannini, M. et al. Spin structure of surface-supported single-molecule magnets from isomorphous replacement and X-ray magnetic circular dichroism. Inorg. Chem. 50, 2911–2917 (2011).
Cornia, A. et al. Energy-barrier enhancement by ligand substitution in tetrairon(iii) single-molecule magnets. Angew. Chem. Int. Ed. 43, 1136–1139 (2004).
Vergnani, L. et al. Magnetic bistability of isolated giant-spin centers in a diamagnetic crystalline matrix. Chem. Eur. J. 18, 3390–3398 (2012).
Kumar, P. et al. Origin and reduction of 1/f magnetic flux noise in superconducting devices. Phys. Rev. Appl. 6, 041001 (2016).
Wang, H. et al. Candidate source of flux noise in SQUIDs: adsorbed oxygen molecules. Phys. Rev. Lett. 115, 077002 (2015).
Poole, C. P., Farach, H. A., Creswick, R. J. & Prozorov, R. Superconductivity (Elsevier Science, 2014).
Prozorov, R. Equilibrium topology of the intermediate state in type-I superconductors of different shapes. Phys. Rev. Lett. 98, 257001 (2007).
Prozorov, R., Giannetta, R. W., Polyanskii, A. A. & Perkins, G. K. Topological hysteresis in the intermediate state of type-I superconductors. Phys. Rev. B 72, 212508 (2005).
Ruoß, S., Stahl, C., Weigand, M., Schütz, G. & Albrecht, J. High-resolution dichroic imaging of magnetic flux distributions in superconductors with scanning X-ray microscopy. Appl. Phys. Lett. 106, 022601 (2015).
Car, P.-E. et al. Giant field dependence of the low temperature relaxation of the magnetization in a dysprosium(iii)–DOTA complex. Chem. Commun. 47, 3751–3753 (2011).
Bozack, M. J. & Bryant, K. W. Elemental lead by XPS. Surf. Sci. Spectra 1, 324–327 (1992).
Nakajima, R., Stöhr, 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).
Brouder, C. Angular dependence of X-ray absorption spectra. J. Phys. Condens. Matter 2, 701–738 (1990).
Hutter, J., Iannuzzi, M., Schiffmann, F. & VandeVondele, J. cp2k: atomistic simulations of condensed matter systems. WIRES Comput. Mol. Sci. 4, 15–25 (2014).
Lippert, G., Hutter, J. & Parrinello, M. A hybrid Gaussian and plane wave density functional scheme. Mol. Phys. 92, 477–488 (1997).
Krack, M. Pseudopotentials for H to Kr optimized for gradient-corrected exchange-correlation functionals. Theor. Chem. Acc. 114, 145–152 (2005).
Zhang, Y. & Yang, W. Comment on “Generalized gradient approximation made simple”. Phys. Rev. Lett. 80, 890–890 (1998).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Sabatini, R., Gorni, T. & de Gironcoli, S. Nonlocal van der Waals density functional made simple and efficient. Phys. Rev. B 87, 041108 (2013).
Caneschi, A., Gatteschi, D. & Totti, F. Molecular magnets and surfaces: a promising marriage. A DFT insight. Coord. Chem. Rev. 289–290, 357–378 (2015).
Bencini, A. & Totti, F. A few comments on the application of density functional theory to the calculation of the magnetic structure of oligo-nuclear transition metal clusters. J. Chem. Theory Comput. 5, 144–154 (2009).
We acknowledge SOLEIL for provision of the synchrotron radiation facilities. We thank P. Ohresser, J. P. Kappler and L. Joly for the realization of the ULT-XMCD set-up and for assistance in using the DEIMOS beamline. The European COST Action CA15128 MOLSPIN, the Quantera ERA-NET Co-fund project SUMO and the FET Open Femtoterabyte project are acknowledged for financial support. Italian MIUR, through PRIN project QCNaMoS (2015-HYFSRT) and Progetto Dipartimenti di Eccellenza 2018-2022 (ref. no. B96C1700020008), and Fondazione Ente Cassa di Risparmio di Firenze are also acknowledged for financial support. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (ERC-2014-StG-633818-dasQ) and from French LabEx PALM (ANR-10-LABX-0039-PALM)
The authors declare no competing interests.
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(a) Magnification of the STM image of Fe4SMe/Pb(111) in Fig. 2a (main text). Orange and pink lines indicate the molecular easy axis projections on the surface. (b) Scheme of the 12 observed orientations of the easy axis projection with respect to the crystallographic directions of the Pb(111) surface. The projection of the easy axis lies along the main crystallographic directions of Pb(111), orange lines, or at 30° from them, pink lines (only \([\bar 110]\) is shown in the STM image for convenience). (c) Low Energy Electron Diffraction (LEED), 60 eV, of the clean Pb(111) crystal used to identify the main crystallographic directions of the substrate, x axis corresponding to the STM scanning direction.
Magnification of the STM image of Fe4SMe/Pb(111) in Fig. 2b (main text). Single (1) and double (2) row arrangements of the triangular molecular Fe4SMe superstructures are highlighted.
Top view of three Fe4SMe molecules on Pb(111) calculated by DFT; pink lines indicate the projections of molecular C3 axes. This structure allows to explain the experimental STM topography of Fig. 2c.
(a) TDOS for Fe4SMe/Pb(111) (purple curve), and pDOS contributions from Fe4SMe (blue curve) and Pb(111) surface (red curve). A full width at half-maximum (FWHM) σ=0.45 eV was used. (b) pDOS of atomic contributions in Fe4SMe calculated on Fe4SMe/Pb(111) (σ=0.45 eV). (c) Computed spin density for Fe4SMe on Pb(111). The surfaces are drawn for a value of 0.001 unpaired e bohr-3. Blue and pink colours correspond to spin up and spin down calculated spin densities, respectively. In the inset, arrows depict the arrangement of the spin vectors in the S = 5 ground state using the same colour code. We notice that a similarly negligible spin delocalization was observed for VOPc deposited on Pb with the vanadyl moiety pointing up, but the spin density increased significantly when the molecule was deformed by the STM tip (see Ref. 3). Here, a similar effect appears very unlikely due to the lack of spin density on atoms close to the Pb surface.
XAS and XMCD signal measured at the Fe L2,3 edges on Fe4SMe/Pb(111) at θ = 45° (B = 3 T, T = 220 mK).
Extended Data Fig. 6 Hysteresis loops in the superconducting window Comparison of hysteresis loops on superconducting and normal substrates.
(a) Enlarged version of Fig. 4a (main text). (b) Magnetic hysteresis loop (grey spheres) of a monolayer of a Fe4 complex on a normal metal (here on a gold substrate, see Ref. 27) in the same field region as panel a. The dark grey solid line is the hysteresis loop simulated disregarding the effect of the superconductor.
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Serrano, G., Poggini, L., Briganti, M. et al. Quantum dynamics of a single molecule magnet on superconducting Pb(111). Nat. Mater. 19, 546–551 (2020). https://doi.org/10.1038/s41563-020-0608-9
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