<i>Ab initio</i>approach to the ballistic transport through single atoms

Bagrets, A.; Papanikolaou, N.; Mertig, Ingrid

doi:10.1103/physrevb.73.045428

Cited by 13 publications

(18 citation statements)

References 46 publications

(32 reference statements)

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“…The first transmission channel is almost quantized to 1.0G 0 (G 0 = 2e 2 /h, where e is the electron charge and h is Planck's constant) at the Fermi level and above. This is consistent with the experimental measurements using mechanically controllable break junction technique [32] and with the theoretical evaluation based on the screened Korringa-Kohn-Rostoker Green's function method [33]. The second transmission channel is observed to have a sharp and quantized transmission peak only at the energy of +0.5 eV.…”

Section: B Electron Transport Through a Cu Point Contactsupporting

confidence: 88%

Real-space finite-difference calculation method of generalized Bloch wave functions and complex band structures with reduced computational cost

2014

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Generalized Bloch wave functions of bulk structures, which are composed of not only propagating waves but also decaying and growing evanescent waves, are known to be essential for defining the open boundary conditions in the calculations of the electronic surface states and scattering wave functions of surface and junction structures. Electronic complex band structures being derived from the generalized Bloch wave functions are also essential for studying bound states of the surface and junction structures, which do not appear in conventional band structures. We present a novel calculation method to obtain the generalized Bloch wave functions of periodic bulk structures by solving a generalized eigenvalue problem, whose dimension is drastically reduced in comparison with the conventional generalized eigenvalue problem derived by Fujimoto and Hirose [Phys. Rev. B 67, 195315 (2003)]. The generalized eigenvalue problem derived in this work is even mathematically equivalent to the conventional one, and, thus, we reduce computational cost for solving the eigenvalue problem considerably without any approximation and losing the strictness of the formulations. To exhibit the performance of the present method, we demonstrate practical calculations of electronic complex band structures and electron transport properties of Al and Cu nanoscale systems. Moreover, employing atom-structured electrodes and jellium-approximated ones for both of the Al and Si monatomic chains, we investigate how much the electron transport properties are unphysically affected by the jellium parts.

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Section: B Electron Transport Through a Cu Point Contactsupporting

confidence: 88%

Real-space finite-difference calculation method of generalized Bloch wave functions and complex band structures with reduced computational cost

2014

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“…We have performed a quantitative analysis of the eigenchannel contributions to conductance using a recently proposed approach [19,24], which employs a mapping of the transmission matrix τ τ † onto a site and orbitalmomentum KKR basis set. Within this approach we analyze the symmetry of the solutions of the eigenvalue problem for τ τ † .…”

Section: High Lowmentioning

confidence: 99%

Evaluation of conduction eigenchannels of an adatom probed by an STM tip

et al. 2011

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Ballistic conductance through a single atom adsorbed on a metallic surface and probed by a scanning tunneling microscope (STM) tip can be decomposed into eigenchannel contributions, which can be potentially obtained from shot noise measurements. Our density functional theory calculations provide evidence that transmission probabilities of these eigenchannels encode information on the modifications of the adatoms local density of states caused by its interaction with the STM tip. In the case of open shell atoms, this can be revealed in nonmonotonic behavior of the eigenchannel's transmissions as a function of the tip-adatom separation.PACS numbers: 73.63. Rt, 73.40.Gk, 68.37.Ef, 72.25.Mk A deep understanding of the transport properties of atomic size systems is of substantial importance and has received considerable interest, spurred, in particular, by the possible applications of nanoscale conductors in future electronic device technologies. Thanks to advances in scanning tunneling microscopy, it is already possible not only to probe the electronic and magnetic structure of surfaces, but also to explore conduction properties of atomic size systems, such as one-dimensional wires [1], individual organic molecules [2-6], atomic sized contacts [7], or even single atoms [8][9][10][11][12][13]. With regard to the latest case, recent experimental observations by Berndt and coworkers [9,14] revealed a qualitative difference in the conductance behavior depending on whether the STM tip was approaching a clean surface or a single adsorbed atom. Contrary to the sudden and unpredictable jump in the conductance for the clean surface, a smooth and fully reversible transition from the tunneling to the contact regime was observed for Cu(111) and Ag(111) surfaces decorated with Cu, Ag, or Co adatoms. Here an increased bonding of the adatom to the surface, due to a dipolar contribution caused by the redistribution of the surface charge, was believed to play a crucial role [14].The case of magnetic adatoms deposited on nonmagnetic substrates is especially attractive [15] since the characteristic Kondo temperature (T K ) has been observed to be sensitive to modifications of the local density of states (LDOS) at the adatom owing to hybridization of its atomic wave functions with the STM tip [9]. Here we offer yet another LDOS probe. The conductance of the atom-sized contact can be decomposed into contributions from the individual transport eigenchannels. In this communication we argue that the transmission probabilities of these eigenchannels, which in principle can be obtained from the shot noise measurements [16], could serve, in addition to T K , as a sensitive tool to probe the modifications in the local electronic structure of the (magnetic) adatom interacting with the (spin-polarized) STM tip.We present an ab initio study of the tunneling conductance for an STM tip approaching a Cu(001) surface decorated with a single Cu or Co adatom (Fig. 1). Our calculations are based on density functional theory [17] within the screened K...

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“…25 An alternative way of calculating quantum transport is by using the Kubo approach as formulated by Baranger and Stone, 26 relating the current to the dynamical polarization. 27,28 Based on these three general approaches, all codes differ in the way the electronic structure is described. In the first implementations based on density functional theory, the electrodes were treated as jellium which were coupled to the scattering region.…”

Section: Fig 1 (Color Online)mentioning

confidence: 99%

“…15,17,18 Large systems up to devices can be described using semiempirical tight-binding methods for the electronic structure, 13,14,19,29,30 while approaches using DFT for both the description of the electrodes via self-energies and the scattering region promise the highest accuracy. 27,28,[31][32][33][34][35][36][37][38][39][40][41][42][43][44] Among these implementations, various DFT methods have been applied. Transport codes based on Green's functions rely on a localized basis set, limiting this approach to basis sets of numerical orbitals such as Gaussians, 34,42 localized orbitals, 32,33,35,38,45 or wavelets.…”

Section: Fig 1 (Color Online)mentioning

confidence: 99%

One-dimensional ballistic transport with FLAPW Wannier functions

et al. 2012

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We present an implementation of the ballistic Landauer-Büttiker transport scheme in one-dimensional systems based on density functional theory calculations within the full-potential linearized augmented plane-wave (FLAPW) method. In order to calculate the conductance within the Green's function method, we map the electronic structure from the extended states of the FLAPW calculation to Wannier functions, which constitute a minimal localized basis set. Our approach benefits from the high accuracy of the underlying FLAPW calculations, allowing us to address the complex interplay of structure, magnetism, and spin-orbit coupling and is ideally suited to study spin-dependent electronic transport in one-dimensional magnetic nanostructures. To illustrate our approach, we study ballistic electron transport in nonmagnetic Pt monowires with a single stretched bond including spin-orbit coupling, and in ferromagnetic Co monowires with different collinear magnetic alignment of the electrodes with the purpose of analyzing the magnetoresistance when going from tunneling to the contact regime. We further investigate spin-orbit scattering due to an impurity atom. We consider two configurations: a Co atom in a Pt monowire and vice versa. In both cases, the spin-orbit induced band mixing leads to a change of the conductance upon switching the magnetization direction from along the chain axis to perpendicular to it. The main contribution stems from ballistic spin scattering for the magnetic Co impurity in the nonmagnetic Pt monowire, and for the Pt scatterer in the magnetic Co monowire from the band formed from states with d xy and d x 2 −y 2 orbital symmetry. We quantify this effect by calculating the ballistic anisotropic magnetoresistance, which displays values up to as much as 7% for ballistic spin scattering and gigantic values of around 100% for the Pt impurity in the Co wire. In addition, we show that the presence of a scatterer can reduce as well as increase the ballistic anisotropic magnetoresistance.

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Ab initioapproach to the ballistic transport through single atoms

Cited by 13 publications

References 46 publications

Real-space finite-difference calculation method of generalized Bloch wave functions and complex band structures with reduced computational cost

Real-space finite-difference calculation method of generalized Bloch wave functions and complex band structures with reduced computational cost

Evaluation of conduction eigenchannels of an adatom probed by an STM tip

One-dimensional ballistic transport with FLAPW Wannier functions

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