Asymmetry-induced effects in Kondo quantum dots coupled to ferromagnetic leads

Abstract

We study the spin-resolved transport through single-level quantum dots strongly coupled to ferromagnetic leads in the Kondo regime, with a focus on contact and material asymmetry-related effects. By using the numerical renormalization group method, we analyze the dependence of relevant spectral functions, linear conductance and tunnel magnetoresistance on the system asymmetry parameters. In the parallel magnetic configuration of the device the Kondo effect is generally suppressed due to the presence of exchange field, irrespective of system's asymmetry. In the antiparallel configuration, on the other hand, the Kondo effect can develop if the system is symmetric. We show that even relatively weak asymmetry may lead to the suppression of the Kondo resonance in the antiparallel configuration and thus give rise to nontrivial behavior of the tunnel magnetoresistance. In addition, by using the second-order perturbation theory we derive general formulas for the exchange field in both magnetic configurations of the system.

References in corpus (7)

• The numerical renormalization group method for quantum impurity systems
• Sum-rule Conserving Spectral Functions from the Numerical Renormalization Group
• Kondo effect in quantum dots coupled to ferromagnetic leads
• NRG study of the Kondo effect in the presence of itinerant-electron ferromagnetism
• Electric-field controlled spin reversal in a quantum dot with ferromagnetic contacts
• Gate-controlled spin-splitting in quantum dots with ferromagnetic leads in the Kondo regime
• Spin effects in single electron tunneling

Cited by in corpus (5)

• Proximity effect on spin-dependent conductance and thermopower of correlated quantum dots
• Perfect spin polarization in T-shaped double quantum dots due to the spin-dependent Fano effect
• The SU(4) Kondo effect in double quantum dots with ferromagnetic leads
• Strong spin Seebeck effect in Kondo T-shaped double quantum dots
• Nonlocal Andreev Reflections as a Source of Spin Exchange and Kondo Screening