Magnetism of a monolayer of Cr10 molecular wheels deposited on Au(111)
| Autor: | Bartolomé, Elena, Bartolomé, Juan, Ferrari, Ludovica, Sedona, Francesco, Arauzo, Ana B., Panighel, Mirko, Herrero-Albillos, Julia, Rubín, Javier, Herrero Martín, Javier, Mugarza, Aitor, Sambi, Mauro, Bartolomé, Fernando |
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| Rok vydání: | 2019 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | Póster presentado a la XXXVII Reunión Bienal de la Real Sociedad Española de Física celebrada en Zaragoza del 15 al 19 de julio de 2019. The self-assembly of magnetic molecules on supporting surfaces provides potentially very interesting magnetic nano-devices in the fields of high-density information storage, information processing and spintronics. We have previously evaporated wheel molecules of formula {Cr10(OMe)20(O2CCMe3)10}, ({Cr10} from now-on) by direct sublimation in UHV on a Ag(110) single-crystal. In powder form, these molecules show ferromagnetic interactions, therefore, they are good candidates as magnetic molecules in a 2D array. In this work, the molecules are deposited onto the Au(111) surface. The STM image in Fig. 1 shows a monolayer of {Cr10} molecules, self-organized in a quasi-hexagonal 2D network. We have studied three samples: a monolayer (1ML) and a multilayer (14 ML) of {Cr10} on Au(111) as well as the {Cr10} molecular material in bulk, powder form. XMCD measurements were performed at the L2,3 edges of Cr at T=2 K and magnetic field up to B=6T. Magnetization and susceptibility were measured by SQUID magnetometry on the multilayer and the powder sample up to B=14 T. We have measured magnetization of the three samples. Both M(H) and X(T) for the powder sample resemble the curves reported earlier, where the {Cr10} wheels were described in terms of a total molecule spin S=9 ground state, with overall ferromagnetic coupling (XT>0). The overall ferromagnetic coupling is lost by depositing the molecules onto the Au(111) surface on the 14 ML sample (XT< 0). Monte Carlo simulations considering the Cr(III) as Heisenberg S=3/2 spin entities describing the M(H) curves yield quantitative results consistent with this behavior: the evaporation of the molecules into 2D regular arrays on Au(111) weakens the Cr-Cr intramolecular exchange pathways, although maintaining the ground state S=9 found for the randomly oriented powder. The M(H) XMCD determination of the {Cr10} 1ML is coincident with that of the 14 ML, within experimental error. |
| Databáze: | OpenAIRE |
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