New route to enhanced figure of merit at nano scale: effect of Aubry–Andre–Harper modulation

Dey, Moumita; Chakraborty, Suvendu; Maiti, Santanu K.

doi:10.1088/1361-6463/ac360d

Cited by 5 publications

(5 citation statements)

References 60 publications

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“…In this case, the mixing of conducting and localized states is not available, and thus, mobility edge does not appear 13,14 . The existence of non-zero critical point leads to different atypical signatures in physical properties and during the last several years an enormous amount of work has been done in different areas starting from electron transport, spin selective transport phenomena, controlled light propagation, and to name a few [22][23][24][25] .…”

Section: Interplay Between Hopping Dimerization and Quasi-periodicity...mentioning

confidence: 99%

Interplay between hopping dimerization and quasi-periodicity on flux-driven circular current in an incommensurate Su–Schrieffer–Heeger ring

Roy

Ganguly²,

Maiti³

2023

Sci Rep

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We report for the first time the phenomenon of flux-driven circular current in an isolated Su–Schrieffer–Heeger (SSH) quantum ring in presence of cosine modulation in the form of the Aubry–André–Harper (AAH) model. The quantum ring is described within a tight-binding framework, where the effect of magnetic flux is incorporated through Peierls substitution. Depending on the arrangements of AAH site potentials we have two different kinds of ring systems that are referred to as staggered and non-staggered AAH SSH rings. The interplay between the hopping dimerization and quasiperiodic modulation leads to several new features in the energy band spectrum and persistent current which we investigate critically. An atypical enhancement of current with increasing AAH modulation strength is obtained that gives a clear signature of transition from a low conducting phase to a high conducting one. The specific roles of AAH phase, magnetic flux, electron filling, intra- and inter-cell hopping integrals, and ring size are discussed thoroughly. We also study the effect of random disorder on persistent current with hopping dimerization to compare the results with the uncorrelated ones. Our analysis can be extended further in studying magnetic responses of similar kinds of other hybrid systems in presence of magnetic flux.

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Section: Interplay Between Hopping Dimerization and Quasi-periodicity...mentioning

confidence: 99%

Interplay between hopping dimerization and quasi-periodicity on flux-driven circular current in an incommensurate Su–Schrieffer–Heeger ring

Roy

Ganguly²,

Maiti³

2023

Sci Rep

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“…The electronic conductivity, Seebeck coefficient, and power factors have been studied by investigating the effects of pressure [20,21], strains [22][23][24], defects [25], doping [12,26], polytypes [27], superlattices [28,29], and reduced dimension or nanostructures [30,31]. The effects of symmetry of crystal structure on thermoelectric properties [32,33] and the effects of Aubry-Andre-Harper modulation on nanoscale thermoelectrics [34] have been investigated. Advancements have been made recently for the Bi 2 Te 3 nanofilms [28,35], other chalcogenide-based materials [26,[36][37][38], CaMg 2 Bi 2 -based compounds [39] or Mg 3 Sb 2-…”

Section: Introductionmentioning

confidence: 99%

Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance

Zheng

2022

Research

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How to achieve high thermoelectric figure of merit is still a scientific challenge. By solving the Boltzmann transport equation, thermoelectric properties can be written as integrals of a single function, the transport distribution function (TDF). In this work, the shape effects of transport distribution function in various typical functional forms on thermoelectric properties of materials are systematically investigated. It is found that the asymmetry of TDF, characterized by skewness, can be used to describe universally the trend of thermoelectric properties. By defining symmetric and asymmetric TDF functions, a novel skewness is then constructed for thermoelectric applications. It is demonstrated, by comparison with ab initio calculations and experiments, that the proposed thermoelectric skewness not only perfectly captures the main feature of conventional skewness but also is able to predict the thermoelectric power accurately. This comparison confirms the unique feature of our proposed thermoelectric skewness, as well as its special role of connection between the statistics of TDF and thermoelectric properties of materials. It is also found that the thermoelectric performance can be enhanced by increasing the asymmetry of TDF. Finally, it is also interesting to find that the thermoelectric transport properties based on typical quantum statistics (Fermi-Dirac distributions) can be well described by typical shape parameter (skewness) for classical statistics.

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“…The situation becomes very interesting when a correlation is imposed among the site energies. There exist many examples of correlated disordered systems that are widely used to study localization phenomena, and among them, the most notable system is probably the Aubry-André-Harper (AAH) [7][8][9][10][11][12][13][14][15][16][17] where site energies are correlated in the cosine form. Unlike in the 1D random disordered system, a 1D AAH chain provides a finite critical point of phase transition, described by the relation W c = 2t (t being the nearest-neighbor hopping (NNH) strength) [8,[18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Localization Properties of a Quasiperiodic Ladder under Physical Gain and Loss: Tuning of Critical Points, Mixed-Phase Zone and Mobility Edge

et al. 2022

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We explore the localization properties of a double-stranded ladder within a tight-binding framework where the site energies of different lattice sites are distributed in the cosine form following the Aubry–André–Harper (AAH) model. An imaginary site energy, which can be positive or negative, referred to as physical gain or loss, is included in each of these lattice sites which makes the system a non-Hermitian (NH) one. Depending on the distribution of imaginary site energies, we obtain balanced and imbalanced NH ladders of different types, and for all these cases, we critically investigate localization phenomena. Each ladder can be decoupled into two effective one-dimensional (1D) chains which exhibit two distinct critical points of transition from metallic to insulating (MI) phase. Because of the existence of two distinct critical points, a mixed-phase (MP) zone emerges which yields the possibility of getting a mobility edge (ME). The conducting behaviors of different energy eigenstates are investigated in terms of inverse participation ratio (IPR). The critical points and thus the MP window can be selectively controlled by tuning the strength of the imaginary site energies which brings a new insight into the localization aspect. A brief discussion on phase transition considering a multi-stranded ladder was also given as a general case, to make the present communication a self-contained one. Our theoretical analysis can be utilized to investigate the localization phenomena in different kinds of simple and complex quasicrystals in the presence of physical gain and/or loss.

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New route to enhanced figure of merit at nano scale: effect of Aubry–Andre–Harper modulation

Cited by 5 publications

References 60 publications

Interplay between hopping dimerization and quasi-periodicity on flux-driven circular current in an incommensurate Su–Schrieffer–Heeger ring

Interplay between hopping dimerization and quasi-periodicity on flux-driven circular current in an incommensurate Su–Schrieffer–Heeger ring

Asymmetrical Transport Distribution Function: Skewness as a Key to Enhance Thermoelectric Performance

Localization Properties of a Quasiperiodic Ladder under Physical Gain and Loss: Tuning of Critical Points, Mixed-Phase Zone and Mobility Edge

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