The electrical conductance of atomic metal contacts represents a powerful tool for detecting nanomagnetism. Conductance reflects magnetism through anomalies at zero bias(1-7)-generally with Fano line shapes-owing to the Kondo screening of the magnetic impurity bridging the contact(8,9). A full atomic-level understanding of this nutshell many-body system is of the greatest importance, especially in view of our increasing need to control nanocurrents by means of magnetism. Disappointingly, at present, zero-bias conductance anomalies are not calculable from atomistic scratch. Here, we demonstrate a working route connecting approximately but quantitatively density functional theory (DFT) and numerical renormalization group (NRG) approaches and leading to a first-principles conductance calculation for a nanocontact, exemplified by a Ni impurity in a Au nanowire. A Fano-like conductance line shape is obtained microscopically, and shown to be controlled by the impurity s-level position. We also find a relationship between conductance anomaly and geometry, and uncover the possibility of opposite antiferromagnetic and ferromagnetic Kondo screening-the latter exhibiting a totally different and unexplored zero-bias anomaly. The present matching method between DFT and NRG should permit the quantitative understanding and exploration of this larger variety of Kondo phenomena at more general magnetic nanocontacts.

Kondo conductance in an atomic nanocontact from first principles / Lucignano, P.; Mazzarello, R.; Smogunov, A.; Fabrizio, M.; Tosatti, E.. - In: NATURE MATERIALS. - ISSN 1476-1122. - 8:7(2009), pp. 563-567. [10.1038/NMAT2476]

Kondo conductance in an atomic nanocontact from first principles

Fabrizio, M.;Tosatti, E.
2009-01-01

Abstract

The electrical conductance of atomic metal contacts represents a powerful tool for detecting nanomagnetism. Conductance reflects magnetism through anomalies at zero bias(1-7)-generally with Fano line shapes-owing to the Kondo screening of the magnetic impurity bridging the contact(8,9). A full atomic-level understanding of this nutshell many-body system is of the greatest importance, especially in view of our increasing need to control nanocurrents by means of magnetism. Disappointingly, at present, zero-bias conductance anomalies are not calculable from atomistic scratch. Here, we demonstrate a working route connecting approximately but quantitatively density functional theory (DFT) and numerical renormalization group (NRG) approaches and leading to a first-principles conductance calculation for a nanocontact, exemplified by a Ni impurity in a Au nanowire. A Fano-like conductance line shape is obtained microscopically, and shown to be controlled by the impurity s-level position. We also find a relationship between conductance anomaly and geometry, and uncover the possibility of opposite antiferromagnetic and ferromagnetic Kondo screening-the latter exhibiting a totally different and unexplored zero-bias anomaly. The present matching method between DFT and NRG should permit the quantitative understanding and exploration of this larger variety of Kondo phenomena at more general magnetic nanocontacts.
2009
8
7
563
567
https://www.nature.com/articles/nmat2476
https://arxiv.org/abs/0907.3422v1
Lucignano, P.; Mazzarello, R.; Smogunov, A.; Fabrizio, M.; Tosatti, E.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/13511
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