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High Blocking Temperature of Magnetization and Giant Coercivity in the Azafullerene Tb 2 @C 79 N with a Single-Electron Terbium–Terbium Bond
2019, Velkos, Georgios, Krylov, Denis S., Kirkpatrick, Kyle, Spree, Lukas, Dubrovin, Vasilii, Büchner, Bernd, Avdoshenko, Stanislav M., Bezmelnitsyn, Valeriy, Davis, Sean, Faust, Paul, Duchamp, James, Dorn, Harry C., Popov, Alexey A.
The azafullerene Tb 2 @C 79 N is found to be a single-molecule magnet with a high 100-s blocking temperature of magnetization of 24 K and large coercivity. Tb magnetic moments with an easy-axis single-ion magnetic anisotropy are strongly coupled by the unpaired spin of the single-electron Tb−Tb bond. Relaxation of magnetization in Tb 2 @C 79 N below 15 K proceeds via quantum tunneling of magnetization with the characteristic time τ QTM =16 462±1230 s. At higher temperature, relaxation follows the Orbach mechanism with a barrier of 757±4 K, corresponding to the excited states, in which one of the Tb spins is flipped. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
Robust Single Molecule Magnet Monolayers on Graphene and Graphite with Magnetic Hysteresis up to 28 K
2021, Spree, Lukas, Liu, Fupin, Neu, Volker, Rosenkranz, Marco, Velkos, Georgios, Wang, Yaofeng, Schiemenz, Sandra, Dreiser, Jan, Gargiani, Pierluigi, Valvidares, Manuel, Chen, Chia-Hsiang, Büchner, Bernd, Avdoshenko, Stanislav M., Popov, Alexey A.
The chemical functionalization of fullerene single molecule magnet Tb2@C80(CH2Ph) enables the facile preparation of robust monolayers on graphene and highly oriented pyrolytic graphite from solution without impairing their magnetic properties. Monolayers of endohedral fullerene functionalized with pyrene exhibit magnetic bistability up to a temperature of 28 K. The use of pyrene terminated linker molecules opens the way to devise integration of spin carrying units encapsulated by fullerene cages on graphitic substrates, be it single-molecule magnets or qubit candidates. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
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.