Entropy per particle spikes in the transition metal dichalcogenides

Shubnyi, V. O.; Gusynin, V. P.; Sharapov, S. G.; Varlamov, A. A.

doi:10.1063/1.5037559

Cited by 9 publications

(6 citation statements)

References 36 publications

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“…Layered transition-metal dichalcogenides (TMDCs) represent another class of materials whose monoatomic layers are being studied experimentally. We show in this Section based on [44] that similar effects to those discussed in the previous Sections may be observed also in TMDCs. Single layer TMDCs with the composition MX 2 (where M = Mo, W is a transition metal, and X = S, Se, Te is a chalcogen atom) are truly two-dimensional (2D) semiconductors with large band gaps ranging within 12 eV (see, e.g., Refs.…”

Section: Entropy Per Particle In Transition Metal Dichalcogenidessupporting

confidence: 81%

Entropy Signatures of Topological Phase Transitions

Galperin

Grassano

Gusynin

et al. 2018

J. Exp. Theor. Phys.

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We review the behavior of the entropy per particle in various two-dimensional electronic systems. The entropy per particle is an important characteristic of any many body system that tells how the entropy of the ensemble of electrons changes if one adds one more electron. Recently, it has been demonstrated how the entropy per particle of a two-dimensional electron gas can be extracted from the recharging current dynamics in a planar capacitor geometry. These experiments pave the way to the systematic studies of entropy in various crystal systems including novel two-dimensional crystals such as gapped graphene, germanene and silicene. Theoretically, the entropy per particle is linked to the temperature derivative of the chemical potential of the electron gas by the Maxwell relation. Using this relation, we calculate the entropy per particle in the vicinity of topological transitions in various two-dimensional electronic systems. We show that the entropy experiences quantized steps at the points of Lifshitz transitions in a two-dimensional electronic gas with a parabolic energy spectrum. In contrast, in doubled-gapped Dirac materials, the entropy per particles demonstrates characteristic spikes once the chemical potential passes through the band edges. The transition from a topological to trivial insulator phase in germanene is manifested by the disappearance of a strong zero-energy resonance in the entropy per particle dependence on the chemical potential. We conclude that studies of the entropy per particle shed light on multiple otherwise hidden peculiarities of the electronic band structure of novel two-dimensional crystals. CONTENTS

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Section: Entropy Per Particle In Transition Metal Dichalcogenidessupporting

confidence: 81%

Entropy Signatures of Topological Phase Transitions

Galperin

Grassano

Gusynin

et al. 2018

J. Exp. Theor. Phys.

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“…5. This behavior is similar to the thermopower of biased bilayer graphene [41] and other gapped 2D materials such as germanene under an external electric field [30] and semiconducting dichalcogenides [31]. At room temperature, the DEP in Fig.…”

Section: B Abc-stacked Tlgsupporting

confidence: 72%

“…The DEP is an experimentally measurable quantity in gated 2D electron systems, allowing superior sensitivity in comparison to a.c. calorimetry [28], and can be directly linked to the thermoelectric power or alternatively to the Seebeck coefficient [43]. The DEP, s = ∂S e /∂N is found from the Maxwell relation as [28][29][30][31][32][33]…”

Section: A Differential Electronic Entropy Per Particlementioning

confidence: 99%

“…Both experimental and theoretical studies have revealed the electronic band structure and density of states (DOS) of TLG samples strongly depend on the stacking pattern they possess, showing significant changes under applied electrical potentials [19][20][21][22][23][24][25][26][27]. This makes TLG materials suitable to inspect the EC effect and novel thermodynamic quantities such as the differential entropy per particle (DEP) [28][29][30][31][32][33]. Through Bloch electrons in parametrized tight-binding models linked to Fermi statistics, we show how the thermal response varies within each TLG stacking as a result of the quantum-thermodynamic processes involved at low-energies.…”

Section: Introductionmentioning

confidence: 99%

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Gate-tunable direct and inverse electrocaloric effect in trilayer graphene

Cortés,

Negrete,

Peña

et al. 2021

Preprint

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The electrocaloric (EC) effect is the reversible change in temperature and/or entropy of a material when it is subjected to an adiabatic electric field change. Our tight-binding calculations linked to Fermi statistics, show that the EC effect is sensitive to the stacking arrangement in trilayer graphene (TLG) structures connected to a heat source, and is produced by changes of the electronic density of states (DOS) near the Fermi level when external gate fields are applied on the outer graphene layers. We demonstrate the AAA-stacked TLG presents an inverse EC response (cooling), whereas the EC effect in ABC-stacked TLG remains direct (heating) regardless of the applied gate field potential strength. We reveal otherwise the TLG with Bernal-ABA stacking geometry generates both the inverse and direct EC response in the same sample, associated with a gate-dependent electronic entropy transition at finite temperature. By varying the chemical potential to different Fermi levels, we find maxima and minima of the DOS are located near the extremes of the electronic entropy, which are correlated with sign changes in the differential entropy per particle, giving a particular experimentally measurable electronic entropy spectrum for each TLG geometry. The EC effect in quantum two-dimensional layered systems may bring a wide variety of prototype van der Waals materials that could be used as versatile platforms to controlling the temperature in nanoscale electronic devices required in modern portable on-chip technologies.

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“…Under certain conditions, the effects of size quantization appear in the observed thermodynamic quantities even in the absence of a magnetic field [16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

On the Heat Capacity of a Quasi-Two-Dimensional Electron Gas

Baymatov

Gulyamov

Abdulazizov

2019

Advances in Condensed Matter Physics

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Numerical and analytical results of the investigation of the thermodynamic properties of a quasi-2D electron gas are presented. The density of states, the temperature derivative of the chemical potential, and the heat capacity of the gas at the resonance points and away from it are analyzed. It is shown that, in the dependence of the heat capacity on the chemical potential, there are additional steps at the resonance points. The width of the additional steps increases with temperature. With the increase in temperature, when the main steps are practically blurred, there are still visible marks from the additional steps.

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Entropy per particle spikes in the transition metal dichalcogenides

Cited by 9 publications

References 36 publications

Entropy Signatures of Topological Phase Transitions

Entropy Signatures of Topological Phase Transitions

Gate-tunable direct and inverse electrocaloric effect in trilayer graphene

On the Heat Capacity of a Quasi-Two-Dimensional Electron Gas

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