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Magnetic Hysteresis at 10 K in Single Molecule Magnet Self‐Assembled on Gold
2021, Chen, Chia-Hsiang, Spree, Lukas, Koutsouflakis, Emmanouil, Krylov, Denis S., Liu, Fupin, Brandenburg, Ariane, Velkos, Georgios, Schimmel, Sebastian, Avdoshenko, Stanislav M., Federov, Alexander, Weschke, Eugen, Choueikani, Fadi, Ohresser, Philippe, Dreiser, Jan, Büchner, Bernd, Popov, Alexey A.
Tremendous progress in the development of single molecule magnets (SMMs) raises the question of their device integration. On this route, understanding the properties of low‐dimensional assemblies of SMMs, in particular in contact with electrodes, is a necessary but difficult step. Here, it is shown that fullerene SMM self‐assembled on metal substrate from solution retains magnetic hysteresis up to 10 K. Fullerene‐SMM DySc2N@C80 and Dy2ScN@C80 are derivatized to introduce a thioacetate group, which is used to graft SMMs on gold. Magnetic properties of grafted SMMs are studied by X‐ray magnetic circular dichroism and compared to the films of nonderivatized fullerenes prepared by sublimation. In self‐assembled films, the magnetic moments of the Dy ions are preferentially aligned parallel to the surface, which is different from the disordered orientation of endohedral clusters in nonfunctionalized fullerenes. Whereas chemical derivatization reduces the blocking temperature of magnetization and narrows the hysteresis of Dy2ScN@C80, for DySc2N@C80 equally broad hysteresis is observed as in the fullerene multilayer. Magnetic bistability in the DySc2N@C80 grafted on gold is sustained up to 10 K. This study demonstrates that self‐assembly of fullerene‐SMM derivatives offers a facile solution‐based procedure for the preparation of functional magnetic sub‐monolayers with excellent SMM performance.
Substrate-Independent Magnetic Bistability in Monolayers of the Single-Molecule Magnet Dy2ScN@C80 on Metals and Insulators
2020, Krylov, Denis S., Schimmel, Sebastian, Dubrovin, Vasilii, Liu, Fupin, Nguyen, T.T. Nhung, Spree, Lukas, Chen, Chia-Hsiang, Velkos, Georgios, Bulbucan, Claudiu, Westerström, Rasmus, Studniarek, Michał, Dreiser, Jan, Hess, Christian, Büchner, Bernd, Avdoshenko, Stanislav M., Popov, Alexey A.
Magnetic hysteresis is demonstrated for monolayers of the single-molecule magnet (SMM) Dy2ScN@C80 deposited on Au(111), Ag(100), and MgO|Ag(100) surfaces by vacuum sublimation. The topography and electronic structure of Dy2ScN@C80 adsorbed on Au(111) were studied by STM. X-ray magnetic CD studies show that the Dy2ScN@C80 monolayers exhibit similarly broad magnetic hysteresis independent on the substrate used, but the orientation of the Dy2ScN cluster depends strongly on the surface. DFT calculations show that the extent of the electronic interaction of the fullerene molecules with the surface is increasing dramatically from MgO to Au(111) and Ag(100). However, the charge redistribution at the fullerene-surface interface is fully absorbed by the carbon cage, leaving the state of the endohedral cluster intact. This Faraday cage effect of the fullerene preserves the magnetic bistability of fullerene-SMMs on conducting substrates and facilitates their application in molecular spintronics. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
Adsorption characteristics of Er3N@C80on W(110) and Au(111) studied via scanning tunneling microscopy and spectroscopy
2017-5-23, Schimmel, Sebastian, Sun, Zhixiang, Baumann, Danny, Krylov, Denis, Samoylova, Nataliya, Popov, Alexey, Büchner, Bernd, Hess, Christian
We performed a study on the fundamental adsorption characteristics of Er3N@C80 deposited on W(110) and Au(111) via room temperature scanning tunneling microscopy and spectroscopy. Adsorbed on W(110), a comparatively strong bond to the endohedral fullerenes inhibited the formation of ordered monolayer islands. In contrast, the Au(111)-surface provides a sufficiently high mobility for the molecules to arrange in monolayer islands after annealing. Interestingly, the fullerenes modify the herringbone reconstruction indicating that the molecule–substrate interaction is of considerable extent. Investigations concerning the electronic structure of Er3N@C80/Au(111) reveals spatial variations dependent on the termination of the Au(111) at the interface.