Abstract
We present a computational method to quantitatively describe the linear-response conductance of nanoscale devices in the Kondo regime. This method relies on a projection scheme to extract an Anderson impurity model from the results of density functional theory and nonequilibrium Green's functions calculations. The Anderson impurity model is then solved by continuous-time quantum Monte Carlo. The developed formalism allows us to separate the different contributions to the transport, including coherent or noncoherent transport channels, and also the quantum interference between impurity and background transmission. We apply the method to a scanning tunneling microscope setup for the 1,3,5-triphenyl-6-oxoverdazyl (TOV) stable radical molecule adsorbed on gold. The TOV molecule has one unpaired electron, which when brought in contact with metal electrodes behaves like a prototypical single Anderson impurity. We evaluate the Kondo temperature, the finite-temperature spectral function, and transport properties, finding good agreement with published experimental results.
Highlights
In recent years, much research effort has been dedicated to study the electronic transport through magnetic molecules and single atoms in order to combine molecular electronics with spintronics [1,2,3]
The spin delocalization over the verdazyl heterocycle reflects the character of the singly occupied molecular orbital (SOMO), and of the corresponding singly unoccupied molecular orbital (SUMO) (Fig. 4, left panel)
We have presented a rigorous way to extract an effective Anderson impurity model (AIM) from density functional theory (DFT)+nonequilibrium Green’s functions (NEGF) calculations for molecules adsorbed on a substrate
Summary
Much research effort has been dedicated to study the electronic transport through magnetic molecules and single atoms in order to combine molecular electronics with spintronics [1,2,3]. The so-called Kondo temperature θK, characteristic of each system, the coupling between the electrons from the electrodes and the spin of the molecule promotes the formation of a many-body state with a fully or partially quenched magnetic moment. This results in a new resonant transport channel at the electrodes’ Fermi level. The Kondo effect has been studied in a number of molecular devices [8,9,14,17,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44], and exotic manifestations, such as the orbital Kondo effect, have been reported [45]
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