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Design of Bistable Gold@Spin-Crossover Core-Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching

preprint
submitted on 03.01.2019 and posted on 04.01.2019 by Ramón Torres-Cavanillas, Rocher Sanchis-Gual, Julien Dugay, Marc Coronado-Puchau, Dr. Mónica Giménez Marqués, Eugenio Coronado

A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)2(trz)](BF4) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of ca.4 nm. Temperature-dependent charge transport measurements of an electrical device based on assemblies of these Au@SCO NPs display well-defined, reproducible and sharp thermal hysteresis loops in the conductance near room temperature. This device is characterized both, by a large change in conductance upon spin state switching, and a remarkable transition abruptness, as compared with other memory devices based on the pristine SCO NPs. As a result, the sensitivity of the device to the spin transition is dramatically improved, with values for the ON/OFF ratio which are an order of magnitude better than the best ones obtained in previous SCO devices.

Funding

EU (COST Action MOLSPIN CA15128, ERC Advanced Grant Mol-2D 788222, and FET-OPEN COSMICS 766726), Spanish MINECO (Unit of Excellence “Maria de Maeztu” MDM-2015-0538 and Project MAT2017-89993-R co-financed by FEDER), and Generalitat Valenciana (Prometeo/2017/066). R.T.-C., R.S.-G. and M.G.-M. thank the Ministerio de Ciencia, Innovación y Universidades for the F.P.I., F.P.U. and Juan de la Cierva Incorporation fellowships, respectively.

History

Email Address of Submitting Author

monica.gimenez-marques@uv.es

Institution

Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, c/ Catedrático José Beltrán 2

Country

Spain

ORCID For Submitting Author

0000-0002-4931-5711

Declaration of Conflict of Interest

no conflict of interests

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