Theory of Quantum Conductance of Atomic and Molecular Bridges

Tsukada, Masaru; Tagami, Katsunori; Hirose, Keikichi; Kobayashi, Nobuhiko

doi:10.1143/jpsj.74.1079

Cited by 36 publications

(34 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The advantage of this method is that it treats the infinitely extended reservoirs (leads) in an exact way. The derivation of this formalism has been based on the Keldysh techniques [4][5][6][7][8][9] . Recently a simple derivation of the NEGF results based on a direct solution of the equations of motion for a non-interacting system of electrons was given in Ref.…”

Section: Introductionmentioning

confidence: 99%

Nonequilibrium Green’s function formalism and the problem of bound states

2006

View full text Add to dashboard Cite

The non-equilibrium Green's function formalism for infinitely extended reservoirs coupled to a finite system can be derived by solving the equations of motion for a tight-binding Hamiltonian.While this approach gives the correct density for the continuum states, we find that it does not lead, in the absence of any additional mechanisms for equilibration, to a unique expression for the density matrix of any bound states which may be present. Introducing some auxiliary reservoirs which are very weakly coupled to the system leads to a density matrix which is unique in the equilibrium situation, but which depends on the details of the auxiliary reservoirs in the non-equilibrium case.

show abstract

Section: Introductionmentioning

confidence: 99%

Nonequilibrium Green’s function formalism and the problem of bound states

2006

View full text Add to dashboard Cite

show abstract

“…Self-energy, density and conductance An important concept in the NEGF formalism is a "self-energy" which describes the amplitude for an electron to leave or enter the wire from the leads (reservoirs) which are maintained at some chemical potentials and temperature [10,[20][21][22][23]. The self-energy is a nonHermitian term in the single-particle Hamiltonian of the wire.…”

Section: Non-equilibrium Green's Function Formalismmentioning

confidence: 99%

“…In this paper, we will use the non-equilibrium Green's function (NEGF) formalism to numerically study the conductance of a quantum wire [10,[20][21][22][23]. Since we will use lattice models and the Hartree-Fock (HF) approximation for dealing with interactions in our numerical studies, we will first discuss those topics in Sec.…”

Section: Introductionmentioning

confidence: 99%

Conductance of quantum wires: A numerical study of effects of an impurity and interactions

Agarwal

Sen

2006

Phys. Rev. B

View full text Add to dashboard Cite

We use the non-equilibrium Green's function formalism and a self-consistent Hartree-Fock approximation to numerically study the effects of a single impurity and interactions between the electrons (with and without spin) on the conductance of a quantum wire. We study how the conductance varies with the wire length, the temperature, and the strengths of the impurity and interactions. The numerical results for the dependence of the conductance on the wire length and temperature are compared with the results obtained from a renormalization group analysis based on the HartreeFock approximation. For the spin-1/2 model with a repulsive on-site interaction or the spinless model with an attractive nearest neighbor interaction, we find that the conductance increases with increasing wire length or decreasing temperature. This can be explained using the Born approximation in scattering theory. For a strong impurity, the conductance is significantly different for a repulsive and an attractive impurity; this is due to the existence of a bound state in the latter case. In general, the large density deviations close to the impurity have an appreciable effect on the conductance at short distances which is not captured by the renormalization group equations.

show abstract

“…5. However, when a magnetic atom (such as Co) or magnetic molecule (such as Cu-phthalocyanine) bridges two nonmagnetic metallic leads, the conductance reflects the presence of the impurity spin and its Kondo screening.…”

Section: Introductionmentioning

confidence: 99%

Magnetic impurities in nanotubes: From density functional theory to Kondo many-body effects

et al. 2013

View full text Add to dashboard Cite

Low temperature electronic conductance in nanocontacts, scanning tunneling microscopy (STM), and metal break junctions involving magnetic atoms or molecules is a growing area with important unsolved theoretical problems. While the detailed relationship between contact geometry and electronic structure requires a quantitative ab initio approach such as density functional theory (DFT), the Kondo many body effects ensuing from the coupling of the impurity spin with metal electrons are most properly addressed by formulating a generalized Anderson impurity model to be solved with, for example, the numerical renormalization group (NRG) method. Since there is at present no seamless scheme that can accurately carry out that program, we have in recent years designed a systematic method for semiquantitatively joining DFT and NRG. We apply this DFT-NRG scheme to the ideal conductance of single wall (4,4) and (8,8) nanotubes with magnetic adatoms (Co and Fe), both inside and outside the nanotube, and with a single carbon atom vacancy. A rich scenario emerges, with Kondo temperatures generally in the Kelvin range, and conductance anomalies ranging from a single channel maximum to destructive Fano interference with cancellation of two channels out of the total four. The configuration yielding the highest Kondo temperature (tens of Kelvins) and a measurable zero bias anomaly is that of a Co or Fe impurity inside the narrowest nanotube. The single atom vacancy has a spin, but a very low Kondo temperature is predicted. The geometric, electronic, and symmetry factors influencing this variability are all accessible, which makes this approach methodologically instructive and highlights many delicate and difficult points in the first principles modeling of the Kondo effect in nanocontacts.

show abstract

Theory of Quantum Conductance of Atomic and Molecular Bridges

Cited by 36 publications

References 38 publications

Nonequilibrium Green’s function formalism and the problem of bound states

Nonequilibrium Green’s function formalism and the problem of bound states

Conductance of quantum wires: A numerical study of effects of an impurity and interactions

Magnetic impurities in nanotubes: From density functional theory to Kondo many-body effects

Contact Info

Product

Resources

About