Splitting efficiency and interference effects in a Cooper pair splitter based on a triple quantum dot with ferromagnetic contacts

Abstract

We theoretically study the spin-resolved subgap transport properties of a Cooper pair splitter based on a triple quantum dot attached to superconducting and ferromagnetic leads. Using the Keldysh Green's function formalism, we analyze the dependence of the Andreev conductance, Cooper pair splitting efficiency, and tunnel magnetoresistance on the gate and bias voltages applied to the system. We show that the system's transport properties are strongly affected by spin dependence of tunneling processes and quantum interference between different local and nonlocal Andreev reflections. We also study the effects of finite hopping between the side quantum dots on the Andreev current. This allows for identifying the optimal conditions for enhancing the Cooper pair splitting efficiency of the device. We find that the splitting efficiency exhibits a nonmonotonic dependence on the degree of spin polarization of the leads and the magnitude and type of hopping between the dots. An almost perfect splitting efficiency is predicted in the nonlinear response regime when the energies of the side quantum dots are tuned to the energies of the corresponding Andreev bound states. In addition, we analyzed features of the tunnel magnetoresistance (TMR) for a wide range of the gate and bias voltages, as well as for different model parameters, finding the corresponding sign changes of the TMR in certain transport regimes. The mechanisms leading to these effects are thoroughly discussed.

References in corpus (17)

• Near-unity Cooper pair splitting efficiency
• Cooper Pair Splitting by means of Graphene Quantum Dots
• Superconducting proximity effect in interacting double-dot systems
• Numerical Renormalization Group Approach to a Quantum Dot Coupled to Normal and Superconducting Leads
• Current and noise correlations in a double dot Cooper pair beam splitter
• Non-local Andreev transport through an interacting quantum dot
• Unconventional Superconductivity in Double Quantum Dots
• Local electrical tuning of the nonlocal signals in a Cooper pair splitter
• Josephson current through interacting double quantum dots with spin-orbit coupling
• Spin-polarized Andreev transport influenced by Coulomb repulsion through two quantum dot system
• Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes
• Superconducting proximity effect and zero-bias anomaly in transport through quantum dots weakly attached to ferromagnetic leads
• Spin correlation and entanglement detection in Cooper pair splitters by current measurements using magnetic detectors
• Double quantum dot Cooper-pair splitter at finite couplings
• Kondo physics in double quantum dot based Cooper pair splitters
• Entanglement-symmetry control in a quantum-dot Cooper-pair splitter
• P-wave Cooper pair splitting

Cited by in corpus (7)

• Nonlocal thermoelectricity in a Cooper-pair splitter
• Enhancement of the thermoelectric effect due to the Majorana zero modes coupled to one quantum-dot system
• Current cross-correlations and waiting time distributions in Andreev transport through Cooper pair splitters based on triple quantum dots
• Double-quantum-dot Andreev molecules: Phase diagrams and critical evaluation of effective models
• Single-photon pump by Cooper-pair splitting
• Kondo Screening of Local Moments in a Triangular Triple Quantum Dot Connected to Normal and Superconducting Leads
• Long-range Cooper pair splitting by chiral Majorana edge states