Current cross-correlations in double quantum dot based Cooper pair splitters with ferromagnetic leads

Wrześniewski, Kacper; Trocha, Piotr; Weymann, Ireneusz

doi:10.1088/1361-648x/aa682d

Cited by 22 publications

(23 citation statements)

References 75 publications

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“…Transport properties of double quantum dots with superconducting contacts have been recently explored both experimentally [7][8][9][10][11][12][13][14]18] and theoretically [19][20][21][22][23][24][25][26][27]. The theoretical investigations were however mostly devoted to transport properties in a relatively weak coupling regime.…”

Section: Introductionmentioning

confidence: 99%

Kondo physics in double quantum dot based Cooper pair splitters

Wrześniewski

Weymann

2017

Phys. Rev. B

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The Andreev transport properties of double quantum dot based Cooper pair splitters with one superconducting and two normal leads are studied theoretically in the Kondo regime. The influence of the superconducting pairing correlations on the local density of states, Andreev transmission coefficient and Cooper pair splitting efficiency is thoroughly analyzed. It is shown that finite superconducting pairing potential quickly suppresses the SU(2) Kondo effect, which can however reemerge for relatively large values of coupling to superconductor. In the SU(4) Kondo regime, a crossover from the SU(4) to the SU(2) Kondo state is found as the coupling to superconductor is enhanced. The analysis is performed by means of the density-matrix numerical renormalization group method

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Section: Introductionmentioning

confidence: 99%

Kondo physics in double quantum dot based Cooper pair splitters

Wrześniewski

Weymann

2017

Phys. Rev. B

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“…4. The general result is that, analogically to a single and double quantum-dot based Cooper pair splitters with ferromagnetic leads 32,44 , in the antiparallel magnetic configuration the positive cross-correlations have higher values, while the negative ones are diminished, which is contrary to the case of the parallel configuration. This is associated with the strong influence of the spin-dependent tunneling on the Andreev transport.…”

Section: B Current Cross-correlationsmentioning

confidence: 98%

“…The correlation function in the sequential tunneling approximation has contributions only from the current operators appearing in two distinct irreducible blocks. 32,44 Therefore, the following expression allows for calculating the cross-correlation function between currents flowing through the left and right junctions 57…”

Section: B Real-time Diagrammatic Techniquementioning

confidence: 99%

Current cross-correlations and waiting time distributions in Andreev transport through Cooper pair splitters based on a triple quantum dot system

Wrześniewski¹,

Weymann²

2020

Phys. Rev. B

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We study the spin-resolved subgap transport in a triple quantum-dot system coupled to one superconducting and two ferromagnetic leads. We examine the Andreev processes in the parallel and antiparallel alignments of ferromagnets magnetic moments in both the linear and nonlinear response regimes. The emphasis is put on the analysis of the current cross-correlations between the currents flowing through the left and right arms of the device and relevant electron waiting time distributions. We show that both quantities can give an important insight into the subgap transport processes and their analysis can help optimizing the system parameters for achieving the considerable Andreev current and efficient Cooper pair splitting. Strong positive values of cross-correlations are associated with the presence of tunneling processes enhancing the Cooper pair splitting efficiency, while short waiting times for electrons tunneling through distinct ferromagnetic contacts indicate fast splitting of emitted Cooper pairs. In particular, we study two detuning schemes and show that antisymmetric shift of side quantum dots energy levels is favorable for efficient Cooper pair splitting. The analysis of spin-resolved waiting time distributions supports the performance enhancement due to the presence of ferromagnetic contacts, which is in particular revealed for short times. Finally, we consider the effect of changing the inter-dot hopping amplitude and predict that strong inter-dot correlations lead to a reduction of Andreev transport properties in low-bias limit.arXiv:2003.09165v1 [cond-mat.mes-hall]

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“…The transport properties of quantum-dot-based CPS are already relatively well understood [13,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Such systems can be modeled by a double quantum dot Anderson-type Hamiltonian, with the two dots coupled to a common superconducting lead and each dot attached to a normal electrode.…”

Section: Introductionmentioning

confidence: 99%

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

2018

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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. arXiv:1805.11130v1 [cond-mat.mes-hall]

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Current cross-correlations in double quantum dot based Cooper pair splitters with ferromagnetic leads

Cited by 22 publications

References 75 publications

Kondo physics in double quantum dot based Cooper pair splitters

Kondo physics in double quantum dot based Cooper pair splitters

Current cross-correlations and waiting time distributions in Andreev transport through Cooper pair splitters based on a triple quantum dot system

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

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