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3 results on '"Rizzini, Alberto Lodi"'

2. Spin Tuning of Electron-Doped Metal-Phthalocyanine Layers.

Author

Stepanow, Sebastian, Rizzini, Alberto Lodi, Krull, Cornelius, Kavich, Jerald, Cezar, Julio C., Yakhou-Harris, Flora, Sheverdyaeva, Polina M., Moras, Paolo, Carbone, Carlo, Ceballos, Gustavo, Mugarza, Aitor, and Gambardella, Pietro

Subjects
*SEMICONDUCTOR doping, *ELECTRON research, *PHTHALOCYANINES, *METAL phthalocyanines, *NUCLEAR spin, *INTERFACES (Physical sciences), *MAGNETS, *COUPLING constants
Abstract

The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and the nature of the spin-carrying metal center, which is further subject to modifications by the adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring the electronic and magnetic characteristics of molecular magnets. Here we present a systematic investigation of the effects of alkali metal doping on the charge state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine (Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy and ligand field multiplet calculations show that Cu(II), Ni(II), and Fe(ll) ions reduce to Cu(l), Ni(l), and Fe(l) upon alkali metal adsorption, whereas Mn maintains its formal oxidation state. The strength of the crystal field at the Ni, Fe, and Mn sites is strongly reduced upon doping. The combined effect of these changes is that the magnetic moment of high- and low-spin ions such as Cu and Ni can be entirely turned off or on, respectively, whereas the magnetic configuration of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the orbital magnetic moment accompanies charge transfer and a transition to a high-spin state. [ABSTRACT FROM AUTHOR]

Published
2014
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3. Tuning graphene doping by carbon monoxide intercalation at the Ni(111) interface

Author

Zhiyu Zou, Sunil Bhardwaj, Virginia Carnevali, Cinzia Cepek, Sara Fiori, Cristina Africh, Simone del Puppo, Francesca Zarabara, Laerte L. Patera, Mirco Panighel, Maria Peressi, Daniele Perilli, Giovanni Comelli, Erik Zupanič, Cristiana Di Valentin, Gabriele Fornasier, Alberto Lodi Rizzini, Del Puppo, S, Carnevali, V, Perilli, D, Zarabara, F, Rizzini, A, Fornasier, G, Zupanic, E, Fiori, S, Patera, L, Panighel, M, Bhardwaj, S, Zou, Z, Comelli, G, Africh, C, Cepek, C, Di Valentin, C, Peressi, M, Del Puppo, Simone, Carnevali, Virginia, Perilli, Daniele, Zarabara, Francesca, Rizzini, Alberto Lodi, Fornasier, Gabriele, Zupanič, Erik, Fiori, Sara, Patera, Laerte L., Panighel, Mirco, Bhardwaj, Sunil, Zou, Zhiyu, Comelli, Giovanni, Africh, Cristina, Cepek, Cinzia, Di Valentin, Cristiana, and Peressi, Maria

Subjects
Materials science, Photoemission spectroscopy, Intercalation (chemistry), doping, 02 engineering and technology, Electronic structure, 010402 general chemistry, 01 natural sciences, carbon monoxide, law.invention, numerical simulations, chemistry.chemical_compound, intercalation, law, Monolayer, Doping, Intercalation, General Materials Science, Carbon monoxide, low-energy electron diffraction, photoemission spectroscopy, Graphene-substrate interface, Graphene, graphene, scanning tunnelling microscopy, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, chemistry, Electron diffraction, Chemical physics, numerical simulation, Density functional theory, 0210 nano-technology
Abstract

Under near-ambient pressure conditions, carbon monoxide molecules intercalate underneath an epitaxial graphene monolayer grown on Ni(111), getting trapped into the confined region at the interface. On the basis of ab-initio density functional theory calculations, we provide here a full investigation of the intercalated CO pattern, highlighting the modifications induced on the graphene electronic structure. For a CO coverage as low as 0.14 monolayer (ML), the graphene layer is spatially decoupled from the metallic substrate, with a significant C 1s core level shift towards lower binding energies. The most relevant signature of the CO intercalation is a clear switching of the graphene doping state, which changes from n-type, when strongly interacting with the metal surface, to p-type. The shift of the Dirac cone linearly depends on the CO coverage, reaching about 0.9 eV for the saturation value of 0.57 ML. Theoretical predictions are compared with the results of scanning tunnelling microscopy, low-energy electron diffraction and photoemission spectroscopy experiments, which confirm the proposed scenario for the nearly saturated intercalated CO system. This result opens the way to the application of the graphene/Ni(111) interface as gas sensor to easily detect and quantify the presence of carbon monoxide.

Published
2021
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