Coherent electronic transport and Kondo resonance in magnetic nanostructures

Bułka, Bogdan R.; Lipiński, S.

doi:10.1103/physrevb.67.024404

Cited by 67 publications

(56 citation statements)

References 34 publications

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“…In particular, the Friedel sum-rule is violated by ∼ 30%, invalidating the assumptions made in previous studies. 11,19,21 We then derive the local spin-susceptibility on the dot and demonstrate that the full self-consistent solution of the EOM, as used in this work, is required in order to obtain quantitatively correct results. We also examine the local density of states at the Fermi level, and find that it shows the expected universal behavior as function of T /T K , though the EOM Kondo temperature lacks a factor of two in the exponential dependence on the single-energy level on the dot.…”

Section: Introductionmentioning

confidence: 97%

Applicability of the equations-of-motion technique for quantum dots

2006

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The equations-of-motion (EOM) hierarchy satisfied by the Green functions of a quantum dot embedded in an external mesoscopic network is considered within a high-order decoupling approximation scheme. Exact analytic solutions of the resulting coupled integral equations are presented in several limits. In particular, it is found that at the particle-hole symmetric point the EOM Green function is temperature-independent due to a discontinuous change in the imaginary part of the interacting self-energy. However, this imaginary part obeys the Fermi liquid unitarity requirement away from this special point, at zero temperature. Results for the occupation numbers, the density of states and the local spin susceptibility are compared with exact Fermi liquid relations and the Bethe ansatz solution. The approximation is found to be very accurate far from the Kondo regime. In contrast, the description of the Kondo effect is valid on a qualitative level only. In particular, we find that the Friedel sum rule is considerably violated, up to 30%, and the spin susceptibility is underestimated. We show that the widely-used simplified version of the EOM method, which does not account fully for the correlations on the network, fails to produce the Kondo correlations even qualitatively.

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Section: Introductionmentioning

confidence: 97%

Applicability of the equations-of-motion technique for quantum dots

2006

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“…The possibility of the Kondo effect in a quantum dot attached to ferromagnetic electrodes was discussed in a number of papers [137,139,143,212,229,230,231,232,233,234,235]. It was shown, that the Kondo resonance in the parallel configuration is split and suppressed in the presence of ferromagnetic leads [139,231,232,235,234].…”

Section: Multi-level Quantum Dots Based On Single-wall Carbon Nanotubesmentioning

confidence: 99%

Spin effects in single-electron tunnelling

Barnaś¹,

Weymann²

2008

J. Phys.: Condens. Matter

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Abstract. An important consequence of the discovery of giant magnetoresistance in metallic magnetic multilayers is a broad interest in spin dependent effects in electronic transport through magnetic nanostructures. An example of such systems are tunnel junctions -single-barrier planar junctions or more complex ones. In this review we present and discuss recent theoretical results on electron and spin transport through ferromagnetic mesoscopic junctions including two or more barriers. Such systems are also called ferromagnetic single-electron transistors. We start from the situation when the central part of a device has the form of a magnetic (or nonmagnetic) metallic nanoparticle. Transport characteristics reveal then single-electron charging effects, including the Coulomb staircase, Coulomb blockade, and Coulomb oscillations. Single-electron ferromagnetic transistors based on semiconductor quantum dots and large molecules (especially carbon nanotubes) are also considered. The main emphasis is placed on the spin effects due to spin-dependent tunnelling through the barriers, which gives rise to spin accumulation and tunnel magnetoresistance. Spin effects also occur in the current-voltage characteristics, (differential) conductance, shot noise, and others. Transport characteristics in the two limiting situations of weak and strong coupling are of particular interest. In the former case we distinguish between the sequential tunnelling and cotunnelling regimes. In the strong coupling regime we concentrate on the Kondo phenomenon, which in the case of transport through quantum dots or molecules leads to an enhanced conductance and to a pronounced zero-bias Kondo peak in the differential conductance.

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“…from the minimum of the free energy with respect to the mean values of boson operators and Lagrange multipliers. SBMFA best works close to the unitary Kondo limit, but it gives also reliable results of linear conductance for systems with weakly broken symmetry in a relatively wide dot level range, being in a reasonably agreement with experiment and with renormalization group calculations [28,37,[63][64][65][66]. Current flowing through CNTQD in the (mσ) channel can be expressed as …”

Section: Model and Slave Boson Mean-field Formulationmentioning

confidence: 73%

Intra- and inter-shell Kondo effects in carbon nanotube quantum dots

Krychowski¹,

Lipiński²

2018

Eur. Phys. J. B

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Abstract. The linear response transport properties of carbon nanotube quantum dot in the strongly correlated regime are discussed. The finite-U mean field slave boson approach is used to study many-body effects. Magnetic field can rebuilt Kondo correlations, which are destroyed by the effect of spin-orbit interaction or valley mixing. Apart from the field induced revivals of SU(2) Kondo effects of different types: spin, valley or spin-valley, also more exotic phenomena appear, such as SU(3) Kondo effect. Threefold degeneracy occurs due to the effective intervalley exchange induced by short-range part of Coulomb interaction or due to the intershell mixing. In narrow gap nanotubes the full spin-orbital degeneracy might be recovered in the absence of magnetic field opening the condition for a formation of SU(4) Kondo resonance.

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Coherent electronic transport and Kondo resonance in magnetic nanostructures

Cited by 67 publications

References 34 publications

Applicability of the equations-of-motion technique for quantum dots

Applicability of the equations-of-motion technique for quantum dots

Spin effects in single-electron tunnelling

Intra- and inter-shell Kondo effects in carbon nanotube quantum dots

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