Spin-resolved thermal signatures of Majorana-Kondo interplay in double quantum dots

Majek, Piotr; Wójcik, Krzysztof P.; Weymann, Ireneusz

doi:10.1103/physrevb.105.075418

Cited by 27 publications

(7 citation statements)

References 91 publications

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“…This value of is different from that for metallic chains where . Violation of the Wiedemann–Franz law has been found in interacting systems 21 , 59 and in devices with interacting quantum dots 60 , 61 .…”

Section: Results Of the Diatomic Sp Or Rice–mele C...mentioning

confidence: 99%

Thermoelectric properties of topological chains coupled to a quantum dot

Lima

Bento

Correa

et al. 2023

Sci Rep

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Topological one-dimensional superconductors can sustain zero energy modes protected by different kinds of symmetries in their extremities. Observing these excitations in the form of Majorana fermions is one of the most intensive quests in condensed matter physics. We are interested in another class of one-dimensional topological systems in this work, namely topological insulators. Which present symmetry-protected end modes with robust properties and do not require the low temperatures necessary for topological superconductivity. We consider a device in the form of a single electron transistor coupled to the simplest kind of topological insulators, namely chains of atoms with hybridized sp orbitals. We study the thermoelectric properties of the device in the trivial, non-trivial topological phases and at the quantum topological transition of the chains. We show that the device’s electrical conductance and the Wiedemann–Franz ratio at the topological transition have universal values at very low temperatures. The conductance and thermopower of the device with diatomic sp-chains, at their topological transition, give direct evidence of fractional charges in the system. The former has an anomalous low-temperature behavior, attaining a universal value that is a consequence of the double degeneracy of the system due to the presence of zero energy modes. On the other hand, the system can be tuned to exhibit high values of the thermoelectric figure of merit and the power factor at high temperatures.

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Section: Results Of the Diatomic Sp Or Rice–mele C...mentioning

confidence: 99%

Thermoelectric properties of topological chains coupled to a quantum dot

Lima

Bento

Correa

et al. 2023

Sci Rep

View full text Add to dashboard Cite

show abstract

“…We consider a poor man's Majorana fermions, i.e., only one Majorana fermion at the end of the superconductor wire is considered. [28][29][30] The whole system can be modeled by the Hamiltonian [29,[31][32][33][34] H = H wires + H T + H c . The first term stands for the left and right semi-infinite wires, which are modeled as hopping of noninteracting quasiparticles in a line…”

Section: Model and Methodsmentioning

confidence: 99%

“…In fact, many works discuss Hermitian quantum dots interacting with Majorana fermions. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, here we focus on the interplay of PT-symmetric complex potentials, Majorana tunneling and interdot tunneling in a non-Hermitian quantum dot system. We expect that the combination of PT-symmetric complex potentials, Majorana tunneling and interdot tunneling would induce an exceptional point that has not been discussed before.…”

Section: Introductionmentioning

confidence: 99%

Majorana tunneling in a one-dimensional wire with non-Hermitian double quantum dots

Niu 牛,

Luo 罗

2023

Chinese Phys. B

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The combination of non-Hermitian physics and Majorana fermions can give rise to new effects in quantum transport systems. In this work, we investigate the interplay of PT-symmetric complex potentials, Majorana tunneling and inter-dot tunneling in a nonHermitian double quantum dot system. It is found that in weak-coupling regime the Majorana tunneling take pronounced effects to the transport properties of such a system, manifested as splitting the unitary peak into three and a reduced 1/4 peak in transmission function. In the presence of the PT-symmetric complex potentials and inter-dot tunneling, the 1/4 central peak is robust against them, while the two side peaks are tuned by them. The interdot tunneling only induces asymmetry, instead of moving the conductance peak, due to the robustness of Majorana modes. There is an exceptional point induced by the union of Majorana tunneling and inter-dot tunneling. With increased PT-symmetric complex potentials, the two side peaks will move towards each other. When the exceptional point is passed through, these two side peaks will disappear. In strong-coupling regime, Majorana Fermion induces a 1/4 conductance dip instead of the three-peak structure. PT-symmetric complex potentials induce two conductance dips pinned at exceptional point. These effects should be accessible in experiment.

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“…The deviation of the graphene bands from the linear energy dispersion attributed to the valleys

leads to an increase in the optical absorption at high energies [ 46 ]. This highly effective doping can be achieved, for example, through the Majorana transport channel, which is contributed by the scattering mechanism in strongly correlated systems involving, for example, quantum dots [ 47 ].…”

Section: Introductionmentioning

confidence: 99%

Topological Defects Created by Gamma Rays in a Carbon Nanotube Bilayer

2023

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Graphene sheets are a highly radiation-resistant material for prospective nuclear applications and nanoscale defect engineering. However, the precise mechanism of graphene radiation hardness has remained elusive. In this paper, we study the origin and nature of defects induced by gamma radiation in a graphene rolled-up plane. In order to reduce the environmental influence on graphene and reveal the small effects of gamma rays, we have synthesized a novel graphene-based nanocomposite material containing a bilayer of highly aligned carbon nanotube assemblies that have been decorated by organometallic compounds and suspended on nanoporous Al2O3 membranes. The bilayer samples were irradiated by gamma rays from a 137Cs source with a fluence rate of the order of 105 m−2s−1. The interaction between the samples and gamma quanta results in the appearance of three characteristic photon escape peaks in the radiation spectra. We explain the mechanism of interaction between the graphene sheets and gamma radiation using a pseudo-Majorana fermion graphene model, which is a quasi-relativistic N=3-flavor graphene model with a Majorana-like mass term. This model admits the existence of giant charge carrier currents that are sufficient to neutralize the impact of ionizing radiation. Experimental evidence is provided for the prediction that the 661.7-keV gamma quanta transfer enough energy to the electron subsystem of graphene to bring about the deconfinement of the bound pseudo-Majorana modes and involve C atoms in a vortical motion of the electron density flows in the graphene plane. We explain the radiation hardness of graphene by the topological non-triviality of the pseudo-Majorana fermion configurations comprising the graphene charge carriers.

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Spin-resolved thermal signatures of Majorana-Kondo interplay in double quantum dots

Cited by 27 publications

References 91 publications

Thermoelectric properties of topological chains coupled to a quantum dot

Thermoelectric properties of topological chains coupled to a quantum dot

Majorana tunneling in a one-dimensional wire with non-Hermitian double quantum dots

Topological Defects Created by Gamma Rays in a Carbon Nanotube Bilayer

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