Valence band resonant photoemission of Mn12 single molecules grafted on Au(111) surface

Pennino, U. del; Renzi, Valentina De; Biagi, Roberto; Corradini, Valdis; Zobbi, Laura; Cornia, Andrea; Gatteschi, Dante; Bondino, Federica; Magnano, Elena; Zangrando, Marco; Zacchigna, M.; Lichtenstein, Alexander; Boukhvalov, Danil W.

doi:10.1016/j.susc.2006.01.144

Cited by 35 publications

(43 citation statements)

References 20 publications

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“…This is supported by the fact that the possibly radiation-induced final line shape (Fig. 2) is similar to a XAS spectrum presented in [17] where a monolayer of a Mn 12 derivative with long alkyl chain ligands has been investigated. The comparison shows that the molecules [17] have also apparently been degraded by radiation.…”

Section: Resultssupporting

confidence: 76%

“…However, the conservation of the structural, electronic, and magnetic properties of Mn 12 SMMs upon deposition on surfaces could not be unambiguously confirmed so far. X-ray absorption spectroscopy (XAS), resonant photoemission spectroscopy (RPES), and X-ray magnetic circular dichroism (XMCD) are useful techniques to probe the electronic structure of the Mn 12 core and the magnetic properties of Mn 12 molecules [15][16][17][18]. Nevertheless, there are conflicting reports on the structural integrity of Mn 12 molecules deposited on surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, there are conflicting reports on the structural integrity of Mn 12 molecules deposited on surfaces. The authors of [17] claim that the deposition procedure does not affect the intimate cluster nature while the results of [18] indicate a degradation of a different Mn 12 molecule after direct deposition on the Au(111) surface. A decoupling of the molecules from the substrate by means of a functionalization layer seems to allow the deposition of partially intact Mn 12 molecules [18].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the stability of Mn12 single molecule magnets

et al. 2008

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The stability of single crystals and monolayers of Mn 12 single molecule magnets under the influence of X-ray radiation and other possibly disruptive influences has been investigated by means of synchrotron radiation. Clear evidence for radiation induced sample degradation was found for both single crystals and monolayers. The comparison with spectra obtained after damaging the molecules by Ar + sputtering, metal evaporation or water moistening indicates a possibility to distinguish between radiation damage and other external influences. The results clarify some of the previous conflicting reports on the integrity of Mn 12 molecules deposited on surfaces and are linked to the investigations aiming at studies of the electronic and magnetic properties of individual Mn 12 clusters. S. Voss ( ) · M. Fonin · U. Ruediger

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Section: Resultssupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of the stability of Mn12 single molecule magnets

et al. 2008

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“…Recently, molecular junctions based on single-molecule magnets ͑SMMs͒ connected to electrodes or monolayers of SMMs at surfaces, have been fabricated and their electron-transport characteristics [1][2][3][4][5][6] have been measured, as well as their mechanical, electronic, and magnetic properties. [7][8][9][10][11][12][13] Electron transport through an SMM drew a lot of attention because of the intriguing interplay between its transport properties and the internal magnetic degrees of freedom, which is absent in transport through small organic molecules. An SMM consists of several transition metal ions interacting through organic or inorganic ligands via superexchange interactions.…”

Section: Introductionmentioning

confidence: 99%

Effects of bonding type and interface geometry on coherent transport through the single-molecule magnetMn12

et al. 2010

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We examine theoretically coherent electron transport through the single-molecule magnet Mn 12 , bridged between Au͑111͒ electrodes, using the nonequilibrium Green's function method and the density-functional theory. We analyze the effects of bonding type, molecular orientation, and geometry relaxation on the electronic properties and charge and spin transport across the single-molecule junction. We consider nine interface geometries leading to five bonding mechanisms and two molecular orientations: ͑i͒ Au-C bonding, ͑ii͒ Au-Au bonding, ͑iii͒ Au-S bonding, ͑iv͒ Au-H bonding, and ͑v͒ physisorption via van der Waals forces. The two molecular orientations of Mn 12 correspond to the magnetic easy axis of the molecule aligned perpendicular ͓hereafter denoted as orientation ͑1͔͒ or parallel ͓orientation ͑2͔͒ to the direction of electron transport. We find that the electron transport is carried by the lowest unoccupied molecular orbital ͑LUMO͒ level in all the cases that we have simulated. Relaxation of the junction geometries mainly shifts the relevant occupied molecular levels toward the Fermi energy as well as slightly reduces the broadening of the LUMO level. As a result, the current slightly decreases at low bias voltage. Our calculations also show that placing the molecule in the orientation ͑1͒ broadens the LUMO level much more than in the orientation ͑2͒ due to the internal structure of the Mn 12 . Consequently, junctions with the former orientation yield a higher current than those with the latter. Among all of the bonding types considered, the Au-C bonding gives rise to the highest current ͑about one order of magnitude higher than the Au-S bonding͒, for a given distance between the electrodes. The current through the junction with other bonding types decreases in the order of Au-Au, Au-S, and Au-H. Importantly, the spin-filtering effect in all the nine geometries stays robust and their ratios of the majority-spin to the minorityspin transmission coefficients are in the range of 10 3 -10 8 . The general trend in transport among the different bonding types and molecular orientations obtained from this study may be applicable to other single-molecule magnets.

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“…This value of U was selected in order to reproduce photoemission spectra measured for a crystal of Mn 12 molecules. 39 . Our GGA+U calculations show a large gap for the spin-down channel, similar to the low-spin state in the PDOS of Mn(I) (see top right of FIG.…”

Section: Magnetic Anisotropy Barriermentioning

confidence: 99%

Single-molecule magnetMn12on graphene

Fry

Cheng

2014

Phys. Rev. B

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We study energetics, electronic and magnetic structures, and magnetic anisotropy barriers of a monolayer of single-molecule magnets (SMM), [Mn 12 O 12 (COOR) 16 ](H 2 O) 4 (abbreviated as Mn 12 , with R=H, CH 3 , C 6 H 5 and CHCl 2 ), on a graphene surface using spin-polarized density-functional theory with generalized gradient corrections and the inclusion of van der Waals interactions. We find that Mn 12 molecules with ligands -H, -CH 3 , and -C 6 H 5 are physically adsorbed on graphene through weak van der Waals interactions, and a much stronger ionic interaction occurs using a -CHCl 2 ligand. The strength of bonding is closely related to the charge transfer between the molecule and the graphene sheet and can be manipulated by strain in the graphene; specifically, tension enhances n-doping of graphene and compression encourages p-doping. The magnetic anisotropy barrier is computed by including the spin-orbit interaction within density-functional theory. The barriers for the Mn 12 molecules with ligands -H, -CH 3 and -C 6 H 5 on graphene surfaces remain unchanged (within 1 K) from those of isolated molecules because of their weak interaction, and a much larger reduction (10 K) is observed when using the -CHCl 2 ligand on graphene due to a substantial structural deformation as a consequence of the much stronger interaction. Neither strain in graphene nor charge transfer affects the magnetic anisotropy barrier significantly. Finally, we discuss the effect of strong correlation in the high spin state of a Mn 12 SMM and the consequence in SMM-surface adsorption.

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Valence band resonant photoemission of Mn12 single molecules grafted on Au(111) surface

Cited by 35 publications

References 20 publications

Investigation of the stability of Mn12 single molecule magnets

Investigation of the stability of Mn12 single molecule magnets

Effects of bonding type and interface geometry on coherent transport through the single-molecule magnetMn12

Single-molecule magnetMn12on graphene

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