Relation between width of the zero-bias anomaly and Kondo temperaure in transport measurements through correlated quantum dots: Effect of asymmetric coupling to the leads

Abstract

The zero-bias anomaly at low temperatures, originated by the Kondo effect when an electric current flows through a system formed by a spin-$1/2$ quantum dot and two metallic contacts is theoretically investigated. In particular, we compare the width of this anomaly $2T_{\mathrm{NE}}$ with that of the Kondo resonance in the spectral density of states $2T_K^{\rho }$, obtained from a Fano fit of the corresponding curves and also with the Kondo temperature, $T_K^G$, defined from the temperature evolution of the equilibrium conductance $G(T)$. In contrast to $T_K^G$ and $2T_K^{\rho }$, we found that the scale $2T_{\mathrm{NE}}$ strongly depends on the asymmetry between the couplings of the quantum dot to the leads while the total hybridization is kept constant. While the three scales are of the same order of magnitude, $2T_{\mathrm{NE}}$ and $T_K^{\rho }$ agree only in the case of large asymmetry between the different tunneling couplings of the contacts and the quantum dot. On the other hand, for similar couplings, $T_{\mathrm{NE}}$ becomes larger than $T_K^{\rho }$, reaching the maximum deviation, of the order of $30\%$, for identical couplings. The fact that an additional parameter to $T_{\mathrm{NE}}$ is needed to characterize the Kondo effect, weakenig the universality properties, points that some caution should be taken in the usual identification in experiments of the low temperature width of the zero-bias anomaly with the Kondo scale. Furthermore, our results indicate that the ratios $T_{\mathrm{NE}}/T_K^G$ and $T_K^{\rho }/T_K^G$ depend on the range used for the fitting.

11 pages and 10 figures

References in corpus (32)

• Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect
• Orbital Kondo effect in carbon nanotubes
• Quantum phase transition in a single-molecule quantum dot
• Tuning the Kondo effect with a mechanically controllable break junction
• Universal Scaling in Non-equilibrium Transport Through a Single-Channel Kondo Dot
• Long-range Kondo signature of a single magnetic impurity
• Kondo resonances and anomalous gate dependence of electronic conduction in single-molecule transistors
• Berry Phase Oscillations of the Kondo Effect in Single-Molecule Magnets
• Kondo Effects in Carbon Nanotubes: From SU(4) to SU(2) symmetry
• Zero-bias conductance in carbon nanotube quantum dots
• Universal Scaling of Nonequilibrium Transport in the Kondo Regime of Single Molecule Devices
• Thermoelectric characterization of the Kondo resonance in nanowire quantum dots
• Solving quantum impurity problems in and out of equilibrium with variational approach
• Anderson Model out of equilibrium: decoherence effects in transport through a quantum dot
• The Spin-Polarization of the Split Kondo State
• Kondo resonance of a Co atom exchange coupled to a ferromagnetic tip
• Higher-order Fermi-liquid corrections for an Anderson impurity away from half-filling III: non-equilibrium transport
• Shifting the Voltage Drop in Electron Transport through a Single Molecule
• Spin polarized current and shot noise in carbon nanotube quantum dot in the Kondo regime
• Magnetic-Field Dependence of Tunnel Couplings in Carbon Nanotube Quantum Dots
• Universal scaling in nonequilibrium transport through an Anderson impurity
• Enhancing of nonlinear thermoelectric response of a correlated quantum dot in the Kondo regime by asymmetrically coupling to the leads
• Nonequilibrium self-energies, Ng approach and heat current of a nanodevice for small bias voltage and temperature
• Two-color Fermi liquid theory for transport through a multilevel Kondo impurity
• Quantifying the leading role of the surface state in the Kondo effect of Co/Ag(111)
• A thermally driven out-of-equilibrium two-impurity Kondo system
• Spin-Polarized STM for a Kondo adatom
• Non-Fermi liquid behaviour in non-equilibrium transport through Co doped Au chains connected to four-fold symmetric leads
• Width of the charge-transfer peak in the SU(N) impurity Anderson model and its relevance to non-equilibrium transport
• Kondo behavior and conductance through $3d$ impurities in gold chains doped with oxygen
• Leading temperature dependence of the conductance in Kondo-correlated quantum dots
• Kondo temperature when the Fermi level is near a step in the conduction density of states

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