Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes

Abstract

Magnetic field applied to the quantum dot coupled between one metallic and one superconducting electrode can produce a similar effect as has been experimentally observed by Meservey, Tedrow and Fulde [Phys. Rev. Lett. 25, 1270 (1970)] for the planar normal metal -superconductor junctions. We investigate the tunneling current and show that indeed the square root singularities of differential conductance exhibit the Zeeman splitting near the gap edge features V = ±∆/e. Since magnetic field affects also the in-gap states of quantum dot it furthermore imposes a hyperfine structure on the anomalous (subgap) Andreev current which has a crucial importance for a signature of the Kondo resonance.

Andreev reflection through a ferromagnet-quantum dot-superconductor system with intradot Coulomb correlations

“…Our discussion generalizes theoretical analysis of the AR effect in mesoscopic systems proposed previously in [4,6]. The assumption of arbitrary Coulomb correlations extends description of the AR effect to a general case of QD attached to a normal metallic or ferromagnetic external electrode.…”

“…On theoretical side, the effects due to competition between superconducting pairing, Coulomb blockade, spin-flip scattering, interaction with boson field and Zeeman effect have been studied in electronic transport through a system consisting of ferromagnet (F), quantum dot (QD) and superconductor (S) [3][4][5][6][7]. The Andreev reflection in transport through a QD coupled to one or two ferromagnetic electrodes and a superconductor revealed some interesting properties associated with the matching condition for maximum (4e 2 /h) linear conductance and the magnetoresistance effect [3,4].…”

“…Moreover, it is found that when the electron-phonon interactions in the dot are taken into account, new peaks appear on a e-mail: wojrudz@amu.edu.pl both sides of the main AR conductance peak and the splits due to spin-flip scattering appear also in these new satellite peaks [5]. In turn, in [6] the MeserveyTedrow-Fulde effect near the gap-edge energies has been predicted for a quantum dot embedded between normal metallic (nonmagnetic) and superconducting electrodes. The discussion of the latter work revealed also that the on-dot Coulomb interactions impose influence on the in-gap Andreev current leading to the Coulomb satellites in the conductance and can produce a narrow Kondo resonance.…”

Two- and three-terminal far-from-equilibrium thermoelectric nano-devices in the Kondo regime

“…In addition, we measure all energies in units of Γ 0 ≡Γ L . The particle-hole symmetric case is of special importance as it is well known [39] that all previous attempts to use the EOM method failed in this case [58,59]. The issue has been discussed extensively in the literature [43][44][45]; a critical comparison between EOM-based and other approximations has been presented very recently [60].…”

Andreev Conductance through a Quantum Dot Strongly Coupled to Ferromagnetic and Superconducting Leads

“…In a confined geometry, e.g. when S is coupled to N through a quantum dot (QD), such Andreev reflection processes are also possible, leading to the formation of bound states at the S-QD boundary [2], and giving rise to a finite current flowing through the system [3,4]. In the strong coupling regime, the Coulomb correlations on QD may give rise to another interesting phenomenon, namely the Kondo effect [5,6].…”