Impact of Fano and Breit-Wigner resonances in the thermoelectric properties of nanoscale junctions

García‐Suárez, Víctor M.; Ferradás, R.; Ferrer, Jaime

doi:10.1103/physrevb.88.235417

Cited by 40 publications

(42 citation statements)

References 59 publications

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“…[20], Fano and Breit-Wigner-like resonances are expected to enhance the thermopower and figure of merit of nanoscale junctions when the chemical potential crosses these features in the transmission. We will see that this statement is also correct for graphene nanorings.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, quantum interference effects can also play a role in the observed thermoelectric properties of single-molecule heterojunctions [14] and zerodimensional systems [15]. In particular, quantum effects giving rise to Fano resonances in the transmission probability were predicted to have an impact on the thermopower magnitude and the thermoelectric efficiency of quantum dot systems [16][17][18], single-molecule devices [19], and nanoscale junctions [20].…”

Section: Introductionmentioning

confidence: 99%

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Enhancing thermoelectric properties of graphene quantum rings

et al. 2015

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We study the thermoelectric properties of rectangular graphene rings connected symmetrically or asymmetrically to the leads. A side-gate voltage applied across the ring allows for the precise control of the electric current flowing through the system. The transmission coefficient of the rings manifest Breit-Wigner line shapes and/or Fano line shapes, depending on the connection configuration, the width of nanoribbons forming the ring and the side-gate voltage. We find that the thermopower and the figure of merit are greatly enhanced when the chemical potential is tuned close to resonances. Such enhancement is even more pronounced in the vicinity of Fano-like antiresonances which can be induced by a side-gate voltage independently of the geometry. This opens a possibility to use the proposed device as a tunable thermoelectric generator.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancing thermoelectric properties of graphene quantum rings

et al. 2015

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“…Since then nanoscale thermoelectricity has been addressed by an increasing number of theoretical and experimental works; a perspective of the field can be found in the focus point collection in [2] and in the articles appeared in [3]. In particular, interference Ahronov-Bohm [4][5][6][7], Fano [8][9][10][11], Dicke [12,13] and Mach-Zehnder [14,15] effects, inter-and intra-dot correlation effects [16][17][18], coherent transport modification by external magnetic fields and gate voltages. [19][20][21], have been exploited to control the performance of thermoelectric heat devices.…”

Section: Introductionmentioning

confidence: 99%

Analytic treatment of the thermoelectric properties for two coupled quantum dots threaded by magnetic fields

2018

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Coupled double quantum dots (c-2QD) connected to leads have been widely adopted as prototype model systems to verify interference effects on quantum transport at the nanoscale. We provide here an analytic study of the thermoelectric properties of c-2QD systems pierced by a uniform magnetic field. Fully analytic and easy-to-use expressions are derived for all the kinetic functionals of interest. Within the Green's function formalism, our results allow a simple inexpensive procedure for the theoretical description of the thermoelectric phenomena for different chemical potentials and temperatures of the reservoirs, different threading magnetic fluxes, dot energies and interdot interactions; moreover they provide an intuitive guide to parametrize the system Hamiltonian for the design of best performing realistic devices. We have found that the thermopower S can be enhanced by more than ten times and the figure of merit ZT by more than hundred times by the presence of a threading magnetic field. Most important, we show that the magnetic flux increases also the performance of the device under maximum power output conditions. It is worth noticing that in addition to the numerous papers dealing with two quantum dots tunnel-coupled to the leads and between themselves, also Coulomb-coupled quantum dots [24,25] have attracted increasing interest in the recent years [for a general perspective see [26]. This has been motivated by the advances in the fabrication of nano-devices, energy harvesting [22] with quantum dots, and the experimental possibility to taylor TE properties exploiting Coulomb interaction and the charge carriers correlation [27]. Moreover, in recent years parallel coupled quantum dots made of semiconductors with high spin-orbit interaction have proven promising systems to realize two-spin qubit in quantum information processing [28,29].Enhancing thermoelectric performance in linear regimes, requires maximization of the dimensionlesswhere σ is the electrical conductance, S the thermopower (Seebeck) coefficient, T is the temperature and κ=κ e +κ p is the thermal conductance (which includes electronic and lattice contributions). In the search of optimal thermoelectric response of the device, most important quantities are its maximum efficiency as thermoelectric generator, and the efficiency at the maximum of the output power.A crucial aspect both in the implementation of experimental methods [30], and in the evaluation of the thermoelectric response of bulk and nanostructured materials, is the wide parameters range to be explored simultaneously to determine its optimal functioning. In this context, the possibility of using analytic expressions for all the involved thermoelectric functions greatly simplifies the task. In the literature, the analytic treatment of the c-2QD is confined at sufficiently small temperatures by means of the Sommerfeld expansion, extended when necessary to fourth order in k B T in the evaluation of kinetic parameters [9]. In the case of Lorentzian shape of the transmission function, ...

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“…Quantum size effects permit the variation of the electronic properties [5][6][7][8][9] and the reduction of the phonon thermal conductance [10]. Nanopatterning, either with antidots, defects or edge modification, allows for further suppression of phonons [11,12].…”

Section: Introductionmentioning

confidence: 99%

Spin and Charge Caloritronics in Bilayer Graphene Flakes with Magnetic Contacts

et al. 2017

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We investigate the coupling of spin and thermal currents as a means to rise the thermoelectric efficiency of nanoscale graphene devices. We consider nanostructures composed of overlapping graphene nanoribbons with ferromagnetic contacts in different magnetic configurations. Our results show that the charge Seebeck effect is greatly enhanced when the magnetic leads are in an antiparallel configuration, due to the enlargement of the transport gap. However, for the optimization of the charge figure of merit ZT it is better to choose a parallel alignment of the magnetization in the leads, because the electron-hole symmetry is broken in this magnetic configuration. We also obtain the spin-dependent Seebeck coefficient and spin figure of merit. In fact, the spin ZT can double its value with respect to the charge ZT for a wide temperature range, above 300 K. These findings suggest the potential value of graphene nanosystems as energy harvesting devices employing spin currents.

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Impact of Fano and Breit-Wigner resonances in the thermoelectric properties of nanoscale junctions

Cited by 40 publications

References 59 publications

Enhancing thermoelectric properties of graphene quantum rings

Enhancing thermoelectric properties of graphene quantum rings

Analytic treatment of the thermoelectric properties for two coupled quantum dots threaded by magnetic fields

Spin and Charge Caloritronics in Bilayer Graphene Flakes with Magnetic Contacts

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