2006/06/30 by Yoshihide Tanaka, Akira Oguri, A C Hewson +1
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Rare-earth and actinide compounds #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1088/1367-2630/9/5/115
published as New J. Phys. 9 (2007) 115 · 11 pages,11 figs: Equation (A9) has been corrected. It does not affect any other results of the paper
openalex publication_date 2007/05/09 · arxiv created 2007/11/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
Asymmetry in the Josephson couplings between two superconductors through a quantum dot is studied based on a single impurity Anderson model using the numerical renormalization group (NRG). Specifically, we examine how the difference between the couplings Γ L and Γ R affects the ground state, which is known to show a quantum phase transition between a nonmagnetic singlet and a magnetic doublet depending on the various parameters; the Coulomb interaction U , onsite potential , level width caused by the hybridization, and superconducting (SC) gap for the leads on the left and right ( ). Our results show that whether the local moment is fully screened or not depends substantially on the asymmetry in the couplings . It tends to make the singlet ground state stable, while the amplitude and phase difference of the SC gaps tend to suppress the screening. We also discuss some general symmetry properties of the system and their relation to the current conservation.