Quantum-fluctuation effects on the thermopower of a single-electron transistor

Kubala, Björn; König, Jürgen

doi:10.1103/physrevb.73.195316

Cited by 62 publications

(83 citation statements)

References 36 publications

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“…These give rise to qualitatively different effects not captured by O( ) master equations or even approaches that also include tunnel broadening and shifts [37]. For voltages V = ε ↑ − ε ↓ only elastic O( 2 ) tunneling processes are possible which produce a smooth nonexponential background in both ∂I C /∂V (qualitatively similar to that found for metallic islands [27,29]) and ∂I E /∂V . However, above the threshold line V = , indicated in red by (iv) in the schematic Fig.…”

Section: O(mentioning

confidence: 79%

“…Theory mostly focused on the thermopower in the linear-response regime. This includes the study of resonant tunneling [26], inelastic tunneling [27][28][29], and Kondo processes [30][31][32][33]. Works addressing the nonlinear regime have either applied effective single-particle descriptions [34][35][36][37][38] or focused on thermoelectric devices close to resonance assuming weak tunneling [39][40][41] or a weak Coulomb interaction [42].…”

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confidence: 99%

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Charge fluctuations in nonlinear heat transport

et al. 2015

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We show that charge fluctuation processes are crucial for the nonlinear heat conductance through an interacting nanostructure, even far from a resonance. We illustrate this for an Anderson quantum dot accounting for the first two leading orders of the tunneling in a master equation. The often made assumption that off-resonant transport proceeds entirely by virtual occupation of charge states, underlying exchange-scattering models, can fail dramatically for heat transport. The identified energy-transport resonances in the Coulomb blockade regime provide qualitative information about relaxation processes, for instance, by a strong negative differential heat conductance relative to the heat current. These can go unnoticed in the charge current, making nonlinear heat-transport spectroscopy with energy-level control a promising experimental tool. [6]. Here, by analyzing the generic effects of Coulomb interactions on the nonlinear heat transport in nanoscale systems, we will show that this is very promising.Interaction effects have long been probed using gate controlled charge-current spectroscopy, a well-developed experimental tool to access the discrete quantum levels of nanostructures. Two prominent features in the charge current driven by a source-drain voltage underpin this successful method. The first is resonant or single-electron tunneling (SET), which depends on the level position relative to the electrochemical potential, μ R in Fig. 1(a): An electron jumps into or out of an orbital level, directly leading to a real change of its occupancy. The current shows sharp steps as new resonant transport processes are switched on with increasing bias. These processes are routinely identified in a three-terminal setup by plotting the charge conductance as function of the applied bias V and the gate voltage, as exemplified in Fig. 2(a). Two-terminal measurements, e.g., using a scanning probe, correspond to line traces through such a plot. The second type of resonance is independent of the level position and appears as a horizontal line at V = since it originates in the inelastic excitation by an energy at fixed local electron number on the nanostructure. This off-resonant feature requires a second-order tunneling process in which an electron "scatters through," other charge states being only visited virtually [see Fig. 1(b)]. This is known as inelastic electron tunneling (IETS) [7,8] or inelastic cotunneling (ICOT) [9][10][11][12].This inelastic tunneling resonance develops into a nonequilibrium Kondo resonance for low and low temperatures [13][14][15], which is much sharper [11,12] Thermoelectric transport has also been investigated within the two above-mentioned physical transport pictures. Theory mostly focused on the thermopower in the linear-response regime. This includes the study of resonant tunneling [26], inelastic tunneling [27][28][29], and Kondo processes [30][31][32][33]. Works addressing the nonlinear regime have either applied effective single-particle descriptions [34][35][36][37][38] or focused on th...

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confidence: 79%

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confidence: 99%

Charge fluctuations in nonlinear heat transport

et al. 2015

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“…An accurate description of the spectral and transport properties in the most challenging (nonperturbative) regime of intermediate temperatures and bias voltages T, φ T K has however not been feasible until recently. While the electronic transport has been studied extensively, the thermoelectric transport theory mostly focused on the linear response regime 13,25,[71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89] . The nonlinear regime has been addressed mainly in the weak coupling limit 32,78,[90][91][92][93][94][95][96][97] , a systematic analysis including renormalization effects 66,67,98,99 beyond the perturbative regime is still missing.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

et al. 2016

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We study nonequilibrium thermoelectric transport properties of a correlated impurity connected to two leads for temperatures below the Kondo scale. At finite bias, for which a current flows across the leads, we investigate the differential response of the current to a temperature gradient. In particular, we compare the influence of a bias voltage and of a finite temperature on this thermoelectric response. This is of interest from a fundamental point of view to better understand the two different decoherence mechanisms produced by a bias voltage and by temperature. Our results show that in this respect the thermoelectric response behaves differently from the electric conductance. In particular, while the latter displays a similar qualitative behavior as a function of voltage and temperature, both in theoretical and experimental investigations, qualitative differences occur in the case of the thermoelectric response. In order to understand this effect, we analyze the different contributions in connection to the behavior of the impurity spectral function versus temperature. Especially in the regime of strong interactions and large enough bias voltages we obtain a simple picture based on the asymmetric suppression or enhancement of the split Kondo peaks as a function of the temperature gradient. Besides the academic interest, these studies could additionally provide valuable information to assess the applicability of quantum dot devices as responsive nanoscale temperature sensors.

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“…[19]. Two-terminal geometries using mesoscopic conductors have been considered, notably using quantum dots [5,20,21,7,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43]. In the two-terminal geometry, both temperature and voltage bias are applied to the sample and the thermoelectric response is investigated.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric energy harvesting with quantum dots

2014

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Abstract. We review recent theoretical work on thermoelectric energy harvesting in multi-terminal quantum-dot setups. We first discuss several examples of nanoscale heat engines based on Coulomb-coupled conductors. In particular, we focus on quantum dots in the Coulomb-blockade regime, chaotic cavities and resonant tunneling through quantum dots and wells. We then turn towards quantum-dot heat engines that are driven by bosonic degrees of freedom such as phonons, magnons and microwave photons. These systems provide interesting connections to spin caloritronics and circuit quantum electrodynamics.

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Quantum-fluctuation effects on the thermopower of a single-electron transistor

Cited by 62 publications

References 36 publications

Charge fluctuations in nonlinear heat transport

Charge fluctuations in nonlinear heat transport

Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

Thermoelectric energy harvesting with quantum dots

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