Quantum phase transition in a minimal model for the Kondo effect in a Josephson junction

Details Quantum phase transition in a minimal model for the Kondo effect in a Josephson junction Quantum phase transition in a minimal model for the Kondo effect in a Josephson junction

2004-06-12

arxiv.org/abs/cond-mat/0406298v3

J. Phys. Soc. Jpn. 73, 2494 (2004)

Physics

Condensed Matter

Mesoscale and Nanoscale Physics

23 pages, 13 figures, typos are corrected

Scientific paper

10.1143/JPSJ.73.2494

We propose a minimal model for the Josephson current through a quantum dot in a Kondo regime. We start with the model that consists of an Anderson impurity connected to two superconducting (SC) leads with the gaps $\Delta_{\alpha}=|\Delta_{\alpha}| e^{i \theta_{\alpha}}$, where $\alpha = L, R$ for the lead at left and right. We show that, when one of the SC gaps is much larger than the others $|\Delta_L| \gg |\Delta_R|$, the starting model can be mapped exactly onto the single-channel model, which consists of the right lead of $\Delta_R$ and the Anderson impurity with an extra onsite SC gap of $\Delta_d \equiv \Gamma_L e^{i \theta_L}$. Here $\theta_L$ and $\Gamma_L$ are defined with respect to the starting model, and $\Gamma_L$ is the level width due to the coupling with the left lead. Based on this simplified model, we study the ground-state properties for the asymmetric gap, $|\Delta_L| \gg |\Delta_R|$, using the numerical renormalization group (NRG) method. The results show that the phase difference of the SC gaps $\phi \equiv \theta_R -\theta_L$, which induces the Josephson current, disturbs the screening of the local moment to destabilize the singlet ground state typical of the Kondo system. It can also drive the quantum phase transition to a magnetic doublet ground state, and at the critical point the Josephson current shows a discontinuous change. The asymmetry of the two SC gaps causes a re-entrant magnetic phase, in which the in-gap bound state lies close to the Fermi level.

Affiliated with

Also associated with

No associations

Rating

Quantum phase transition in a minimal model for the Kondo effect in a Josephson junction does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Quantum phase transition in a minimal model for the Kondo effect in a Josephson junction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quantum phase transition in a minimal model for the Kondo effect in a Josephson junction will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-507342