Heat dissipation and its relation to thermopower in single-molecule junctions

Zotti, Linda A.; Bürkle, Marius; Pauly, Fabian; Lee, Woochul; Kim, Kyeongtae; Jeong, Wonho; Asai, Yoshihiro; Reddy, Pramod; Cuevas, Juan Carlos

doi:10.1088/1367-2630/16/1/015004

Cited by 94 publications

(114 citation statements)

References 69 publications

(146 reference statements)

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“…This approach is perturbative in the tunneling rates and well controlled in the regime T . While keeping this restriction we recover [46] for U = 0 the corresponding results of the Landauer approach [4,38]. We go beyond standard approaches by including the competition of all tunneling rates O( ) and O( 2 ) (Fig.…”

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confidence: 80%

“…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]. The heat current has received much less attention [39][40][41][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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Charge fluctuations in nonlinear heat transport

et al. 2015

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“…In the Landauer-Büttiker picture the charge current I and the electronic thermal current Q el are given by [38][39][40] …”

Section: B Electronic Transportmentioning

confidence: 99%

“…Details regarding the self-energy correction can be found in Ref. [40]. The electronic contact self energies, on the other hand, are obtained as described in Ref.…”

Section: B Electronic Transportmentioning

confidence: 99%

First-principles calculation of the thermoelectric figure of merit for [2,2]paracyclophane-based single-molecule junctions

et al. 2015

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Here we present a theoretical study of the thermoelectric transport through [2,2]paracyclophane-based singlemolecule junctions. Combining electronic and vibrational structures, obtained from density functional theory (DFT), with nonequilibrium Green's function techniques allows us to treat both electronic and phononic transport properties at a first-principles level. For the electronic part, we include an approximate self-energy correction, based on the DFT+ approach. This enables us to make a reliable prediction of all linear response transport coefficients entering the thermoelectric figure of merit ZT . Paracyclophane derivatives offer a great flexibility in tuning their chemical properties by attaching different functional groups. We show that, for the specific molecule, the functional groups mainly influence the thermopower, allowing us to tune its sign and absolute value. We predict that the functionalization of the bare paracyclophane leads to a largely enhanced electronic contribution Z el T to the figure of merit. Nevertheless, the high phononic contribution to the thermal conductance strongly suppresses ZT . Our work demonstrates the importance to include the phonon thermal conductance for any realistic estimate of the ZT for off-resonant molecular transport junctions. In addition, it shows the possibility of a chemical tuning of the thermoelectric properties for a series of available molecules, leading to equally performing hole-and electron-conducting junctions based on the same molecular framework.

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“…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. Recent findings 90,99 indicate a Seebeck coefficient which is enhanced with respect to the equilibrium result.…”

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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Heat dissipation and its relation to thermopower in single-molecule junctions

Cited by 94 publications

References 69 publications

Charge fluctuations in nonlinear heat transport

Charge fluctuations in nonlinear heat transport

First-principles calculation of the thermoelectric figure of merit for [2,2]paracyclophane-based single-molecule junctions

Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

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