Full-potential linearized augmented plane-wave method for one-dimensional systems: Gold nanowire and iron monowires in a gold tube

Mokrousov, Yuriy; Bihlmayer, Gustav; Blügel, Stefan

doi:10.1103/physrevb.72.045402

Cited by 62 publications

(63 citation statements)

References 43 publications

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“…2(a)]. The same result was obtained by previous ab initio calculations of pure Au chains [16,[21][22][23]. While transport experiments in Au chains indicate that these bands do not cross the Fermi level [24], it has been found that doping with oxygen pushes these bands up, establishing conduction through the 5d xz and 5d yz electrons of Au [25,26].…”

supporting

confidence: 69%

Non-Fermi-Liquid Behavior in Transport Through Co-Doped Au Chains

Napoli

Weichselbaum²,

Roura‐Bas

et al. 2013

Phys. Rev. Lett.

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We calculate the conductance as a function of temperature GðTÞ through Au monatomic chains containing one Co atom as a magnetic impurity, and connected to two conducting leads with a fourfold symmetry axis. Using the information derived from ab initio calculations, we construct an effective model H eff that hybridizes a 3d 7 quadruplet at the Co site with two 3d 8 triplets through the hopping of 5d xz and 5d yz electrons of Au. The quadruplet is split by spin anisotropy due to spin-orbit coupling. SolvingĤ eff with the numerical renormalization group we find that at low temperatures GðTÞ ¼ a À b ffiffiffi ffi T p and the ground state impurity entropy is lnð2Þ=2, a behavior similar to the two-channel Kondo model. Stretching the chain leads to a non-Kondo phase, with the physics of the underscreened Kondo model at the quantum critical point. DOI: 10.1103/PhysRevLett.110.196402 PACS numbers: 71.10.Hf, 73.23.Àb, 75.20.Hr Transport properties in nanoscopic systems are being extensively studied due to potential applications and their role in basic research. In particular, the Kondo effect, in which the spin 1=2 of a molecule or a quantum dot (QD) is screened by one channel of conduction electrons below a characteristic temperature T K , has been experimentally observed and the conductance as a function of temperature GðTÞ is in excellent agreement with theory [1,2]. In spite of the large effect of correlations, these systems are Fermi liquids where, for example, the conductance has the expected behavior GðTÞ ' Gð0Þ À aT 2 for T ( T K , with T K the Kondo temperature and a some constant. More recently, the underscreened Kondo (UK) effect, leading to singular Fermi liquid physics [3,4] has been observed, and quantum phase transitions (QPTs) involving partially Kondo screened spin-1 molecular states were induced by externally controlled parameters [5][6][7].The overscreened Kondo effect, the simplest manifestation of which is the two-channel Kondo (2CK) model, is even more interesting because inelastic scattering persists even at vanishing temperatures and excitation energies. Therefore, the system is a non-Fermi liquid, exhibiting fascinating low-energy properties [8][9][10]. In particular, the impurity contribution to the entropy is lnð2Þ=2 and the conductance per channel at low T has the form GðTÞ ' G 0 =2 AE a ffiffiffi ffi T p , where G 0 is the conductance at zero temperature in the one-channel case. However, experimental observations of 2CK physics have been elusive, particularly due to its instability against the asymmetry of the channels [10]. For example, while 2CK physics is expected to take place at the QPT in the model of two spin-1/2 Kondo impurities [9,10], interchannel charge transfer spoils the quantum critical point (QCP) [10] and its observation in double QD systems [11].Oreg and Goldhaber-Gordon [12] proposed to modify the simplest setup of the one-electron transistor (a QD between two conducting leads) by adding a second large QD with level spacing < T K , which acts as a second channel of conduc...

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confidence: 69%

Non-Fermi-Liquid Behavior in Transport Through Co-Doped Au Chains

Napoli

Weichselbaum²,

Roura‐Bas

et al. 2013

Phys. Rev. Lett.

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“…The explicit one-and two-dimensional implementations also contain a third region, the vacuum region (VR), which can be treated analogously to the IR. 38,39 Thus, the self-consistent spin density is approximated as…”

Section: B Noncollinear Wannier Functions Within the Flapw Methodsmentioning

confidence: 99%

Conductance fingerprints of noncollinear magnetic states in single-atom contacts: A first-principles Wannier-functions study

et al. 2012

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We present a first-principles computational scheme for investigating the ballistic transport properties of onedimensional nanostructures with noncollinear magnetic order. The electronic structure is obtained within density functional theory as implemented in the full-potential linearized augmented plane-wave method and mapped to a tight-binding-like transport Hamiltonian via noncollinear Wannier functions. The conductance is then computed based on the Landauer formula using the Green's function method. As a first application, we study the conductance between two ferromagnetic Co monowires terminated by single Mn apex atoms as a function of Mn-Mn separation. We vary the Mn-Mn separation from the contact (about 2.5 to 5Å) to the far tunneling regime (5 to 10Å). The magnetization direction of the Co electrodes is chosen either in parallel or antiparallel alignment and we allow for different spin configurations of the two Mn spins. In the tunneling and into the contact regime, the conductance is dominated by s-d z 2 states. In the close contact regime (below 3.5Å), there is an additional contribution for a parallel magnetization alignment from the d xz and d yz states which give rise to an increase of the magnetoresistance as it is absent for antiparallel magnetization. If we allow the Mn spins to relax, a noncollinear spin state is formed close to contact due to the competition of ferromagnetic coupling between Mn and Co and antiferromagnetic coupling between the Mn spins. We demonstrate that the transition from a collinear to such a noncollinear spin structure as the two Mn atoms approach leaves a characteristic dip in the distance-dependent conductance and magnetoresistance of the junction. We explain this modification of the spin-valve effect due to the noncollinear spin state based on the spin-dependent hybridization between the d xz,yz states of the Mn spins and their coupling to the Co electrodes.

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“…Various nano conductors have constant valued DOS functions in the energy range of interest [7,13,14,15] hence by taking the DOS function of Eq. (1) as constant and evaluating the integral, an I-V expression without integral calculation for nano conductors is derived as shown in Eq.…”

Section: Presented I-v Expression For Ballistic Nano Conductorsmentioning

confidence: 99%

Algebraic Current-voltage and Voltage Dependent Resistance Expressions for Ballistic Nano Conductors and Their Low Voltage Nonlinearity

Yamaçli

2013

Nano-Micro Lett.

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Abstract:In this study, an algebraic current-voltage (I-V ) equation suitable for the hand-calculation of ballistic nano conductors is derived from Landauer's formulation. A voltage and temperature dependent resistance expression is also obtained. It is shown that the presented algebraic I-V expression and the original Landauer's formula give the same characteristics as expected. Moreover, the I-V characteristics of ballistic nano conductors are investigated and it is concluded that there is an inescapable nonlinearity originating from the curvature of Fermi-Dirac distribution function in low voltage range. Finally, the total harmonic distortion (THD) of a sample ballistic nano conductor caused from its low voltage nonlinearity is computed via HSPICE simulations.

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Full-potential linearized augmented plane-wave method for one-dimensional systems: Gold nanowire and iron monowires in a gold tube

Cited by 62 publications

References 43 publications

Non-Fermi-Liquid Behavior in Transport Through Co-Doped Au Chains

Non-Fermi-Liquid Behavior in Transport Through Co-Doped Au Chains

Conductance fingerprints of noncollinear magnetic states in single-atom contacts: A first-principles Wannier-functions study

Algebraic Current-voltage and Voltage Dependent Resistance Expressions for Ballistic Nano Conductors and Their Low Voltage Nonlinearity

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