Transport in quantum spin Hall edges in contact to a quantum dot

Rizzo, Bruno; Camjayi, Alberto; Arrachea, Liliana

doi:10.1103/physrevb.94.125425

Cited by 5 publications

(6 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fabrication of these elements is nowadays normal in the context of the quantum Hall effect [38][39][40]. However, their realization in the context of the QSH effect remains an experimental challenge so far [41], although they are widely investigated theoretically [42][43][44][45][46][47][48][49][50][51].In the quantum coherent regime the electronic transport properties take place without inelastic scattering and are fully characterized by a transmission function. Particle-hole symmetry breaking is a necessary condition for steady-state heat to work conversion.…”

mentioning

confidence: 99%

Optimal Thermoelectricity with Quantum Spin Hall Edge States

2019

Self Cite

View full text Add to dashboard Cite

We study the thermoelectric properties of a Kramer's pair of helical edge states of the quantum spin Hall effect coupled to a nanomagnet with a component of the magnetization perpendicular to the direction of the spin-orbit interaction of the host. We show that the transmission function of this structure has the desired qualities for optimal thermoelectric performance in the quantum coherent regime. For a single magnetic domain there is a power generation close to the optimal bound. In a configuration with two magnetic domains with different orientations, pronounced peaks in the transmission functions and resonances lead to a high figure of merit. We provide estimates for the fabrication of this device with HgTe quantum-well topological insulators. Introduction.Thermoelectricity in the quantum regime is attracting high interest for some years now [1,2]. Systems hosting edge states, like the quantum Hall and quantum spin Hall are paradigmatic realizations of quantum coherent transport. Several theoretical and experimental results on heat transport and thermoelectricity in these systems have been recently reported .Unlike the quantum Hall state, which is generated by a strong magnetic field, the quantum spin Hall (QSH) state taking place in two-dimensional (2D) topological insulators (TI), preserves time-reversal invariance. Therefore, the edge states appear in helical Kramer's pairs [32][33][34][35][36][37] with opposite spin orientations determined by the spin orbit of the TI. Several heat engines and refrigerators have been recently proposed, taking advantage of the fundamental chiral nature of the quantum Hall edge states, which manifests itself in multiple-terminal structures [19] and in quantum interference [20,21]. Recently, the property of charge fractionalization was also pointed out as a mechanism to enhance thermoelectricity [23]. All these setups rely on the existence of quantum point contacts and quantum dots in the structure, tunnel-coupled to the edge states, which are generated by recourse to constrictions. The fabrication of these elements is nowadays normal in the context of the quantum Hall effect [38][39][40]. However, their realization in the context of the QSH effect remains an experimental challenge so far [41], although they are widely investigated theoretically [42][43][44][45][46][47][48][49][50][51].In the quantum coherent regime the electronic transport properties take place without inelastic scattering and are fully characterized by a transmission function. Particle-hole symmetry breaking is a necessary condition for steady-state heat to work conversion. Having transmission functions rapidly changing in energy within the relevant transport window, is the key to achieve optimal thermoelectricity [2,[52][53][54][55]. The optimal performance is usually quantified by the figure of merit ZT , with the Carnot limit achieved for ZT → ∞. This ideal limit can be realized for transmission functions containing deltafunction like peaks [52]. In this sense, structures with resonant levels like quant...

show abstract

mentioning

confidence: 99%

Optimal Thermoelectricity with Quantum Spin Hall Edge States

2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…When the the Fermi wavelength are longer than the distance between two ferromagnetic electrodes, the spin-dependent scattering can open a gap to form a dot in a systems such as the double HgTe/CdTe quantum well 75 . One can also use QSH edges in contact to the QD 76,77 to form chiral edge states in the central scattering region. When the Fermi energy of QD is inside the energy gap, electrons only tunnel through the unidirectional spin locked edge state, and one can use one edge to transmit spin up electrons and the other edge to transmit spin down electrons.…”

Section: B Waiting Time Distributionsmentioning

confidence: 99%

Spin-resolved electron waiting times in a quantum-dot spin valve

Tang

et al. 2018

Phys. Rev. B

View full text Add to dashboard Cite

We study the electronic waiting time distributions (WTDs) in a non-interacting quantum dot spin valve by varying spin polarization and the noncollinear angle between the magnetizations of the leads using scattering matrix approach. Since the quantum dot spin valve involves two channels (spin up and down) in both the incoming and outgoing channels, we study three different kinds of WTDs, which are two-channel WTD, spin-resolved single-channel WTD and cross-channel WTD. We analyze the behaviors of WTDs in short times, correlated with the current behaviors for different spin polarizations and noncollinear angles. Cross-channel WTD reflects the correlation between two spin channels and can be used to characterize the spin transfer torque process. We study the influence of the earlier detection on the subsequent detection from the perspective of cross-channel WTD, and define the influence degree quantity as the cumulative absolute difference between cross-channel WTDs and first passage time distributions to quantitatively characterize the spin flip process. The influence degree shows a similar behavior with spin transfer torque and can be a new pathway to characterize spin correlation in spintronics system.

show abstract

“…[46][47][48][49][50] Charge transport in helical edges of the quantum spin Hall regime with tunneling contacts between edge states and quantum dots or antidots is a subject of very active theoretical investigation. [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67] arXiv:1808.05570v2 [cond-mat.str-el] 20 Nov 2018…”

Section: Introductionmentioning

confidence: 99%

“…[46][47][48][49][50] Charge transport in helical edges of the quantum spin Hall regime with tunneling contacts between edge states and quantum dots or antidots is a subject of very active theoretical investigation. [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67] The aim of the present work is to analyze the thermoelectric response of quantum spin Hall helical edges realized in the structure sketched in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Helical spin thermoelectrics controlled by a side-coupled magnetic quantum dot in the quantum spin Hall state

2018

Self Cite

View full text Add to dashboard Cite

We study the thermoelectric response of a device containing a pair of helical edge states contacted at the same temperature T and chemical potential µ and connected to an external reservoir, with different chemical potential and temperature, through a side quantum dot. Different operational modes can be induced by applying a magnetic field B and a gate voltage Vg at the quantum dot. At finite B, the quantum dot acts simultaneously as a charge and a spin filter. Charge and spin currents are induced, not only through the quantum dot, but also along the edge states. We focus on linear response and analyze the regimes, which we identify as charge heat engines or refrigerator, spin heat engine and spin refrigerator.PACS numbers:

show abstract

Transport in quantum spin Hall edges in contact to a quantum dot

Cited by 5 publications

References 60 publications

Optimal Thermoelectricity with Quantum Spin Hall Edge States

Optimal Thermoelectricity with Quantum Spin Hall Edge States

Spin-resolved electron waiting times in a quantum-dot spin valve

Helical spin thermoelectrics controlled by a side-coupled magnetic quantum dot in the quantum spin Hall state

Contact Info

Product

Resources

About