Effects of bonding type and interface geometry on coherent transport through the single-molecule magnet Mn-12

dc.contributorVirginia Techen
dc.contributor.authorPark, K.en
dc.contributor.authorBarraza-Lopez, S.en
dc.contributor.authorGarcia-Suarez, V. M.en
dc.contributor.authorFerrer, J.en
dc.contributor.departmentPhysicsen
dc.date.accessed2014-04-23en
dc.date.accessioned2014-05-07T15:36:55Zen
dc.date.available2014-05-07T15:36:55Zen
dc.date.issued2010-03en
dc.description.abstractWe examine theoretically coherent electron transport through the single-molecule magnet Mn-12, bridged between Au(111) 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: (i) Au-C bonding, (ii) Au-Au bonding, (iii) Au-S bonding, (iv) Au-H bonding, and (v) 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 (1)] or parallel [orientation (2)] to the direction of electron transport. We find that the electron transport is carried by the lowest unoccupied molecular orbital (LUMO) 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 (1) broadens the LUMO level much more than in the orientation (2) 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 bonding), 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 minority-spin 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.en
dc.description.sponsorshipNSF DMR-0804665en
dc.description.sponsorshipJeffress Memorial Trust Fundsen
dc.description.sponsorshipSpanish Ministerio de Ciencia e Innovacionen
dc.description.sponsorshipMarie Curie European ITNs FUNMOLS and NANOCTMen
dc.description.sponsorshipMEC FIS2006-12117en
dc.description.sponsorshipNational Center for Supercomputing Applications DMR060011en
dc.description.sponsorshipVirginia Tech Linux clusters and Advanced Research Computingen
dc.identifier.citationPark, K.; Barraza-Lopez, S.; Garcia-Suarez, V. M.; Ferrer, J., "Effects of bonding type and interface geometry on coherent transport through the single-molecule magnet Mn-12," Phys. Rev. B 81, 125447 DOI: http://dx.doi.org/10.1103/PhysRevB.81.125447en
dc.identifier.doihttps://doi.org/10.1103/PhysRevB.81.125447en
dc.identifier.issn1098-0121en
dc.identifier.urihttp://hdl.handle.net/10919/47834en
dc.identifier.urlhttp://journals.aps.org/prb/abstract/10.1103/PhysRevB.81.125447en
dc.language.isoen_USen
dc.publisherAmerican Physical Societyen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjecttotal-energy calculationsen
dc.subjecthigh-spin moleculesen
dc.subjectwave basis-seten
dc.subjectjunctionen
dc.subjectconductanceen
dc.subjectelectronic-structureen
dc.subjectmagnetizationen
dc.subjectsurfaceen
dc.subjectgolden
dc.subjectresistanceen
dc.subjectspectroscopyen
dc.subjectphysics, condensed matteren
dc.titleEffects of bonding type and interface geometry on coherent transport through the single-molecule magnet Mn-12en
dc.title.serialPhysical Review Ben
dc.typeArticle - Refereeden

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