Entropy-Seebeck ratio as a tool for elementary charge determination

summary

The gist

The gist: The ratio of differential entropy per particle to the Seebeck coefficient converges to the elementary charge across an energy window in gapped armchair silicene nanoribbons, establishing a

In short

The study investigates how transport properties (Seebeck coefficient S) and thermodynamic properties (differential entropy per particle s) relate in armchair silicene nanoribbons. The ratio s/S converges to the elementary charge 'e' within the band gap energy region, providing a reliable method to determine 'e' and assess band gap cleanliness.

Key concepts

Seebeck Coefficient (S): This measures the voltage drop in a material when a temperature gradient is applied. It is related to how electronic transmission changes with energy, capturing transport properties through the energy dependence of electron movement in the system.
Differential Entropy per Particle (DEP, s): This is a thermodynamic quantity linked directly to the total electronic entropy of the system. It offers a direct way to estimate S without needing complex explicit electronic transport calculations.
Elementary Charge (e): The fundamental unit of electric charge in electromagnetism. The paper uses the ratio s/S to find this value, showing that when s/S equals e, it confirms the material's electronic structure is clean within a band gap.

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This episode discusses

Entropy-Seebeck ratio as a tool for elementary charge determination · Paper Radio

The paper

Entropy-Seebeck ratio as a tool for elementary charge determination · Read on arXiv

Departamento de F࿚sica, Universidad Técnica Federico Santa Mar໚

In this work, we investigate the relationship between the Seebeck coefficient (S), and the differential entropy per particle (DEP, s), as a tool for characterizing charge carriers in two-dimensional systems. Using armchair silicene nanoribbons as a model platform, we analyze how both quantities and their ratio depend on chemical potential at room temperature. While the Seebeck coefficient captures transport properties through the energy dependence of the electronic transmission, the DEP is directly connected to the system's electronic entropy, offering a direct thermodynamic alternative for estimating S. We evaluate these transport-thermodynamic properties considering diverse ribbon widths, defining metallic and semiconducting regimes. We find both quantities S and s, are highly interconnected within the ribbon's band gap energy region, and their ratio s/S converges to the elementary charge e across that energy window, fulfilling the Kelvin formula S=s/e. On the contrary, s/S is undefined for gapless ribbons in the energy window of the first transmission channel. These results establish the ratio between the DEP and the Seebeck coefficient as a reliable and complementary probe for the determination of the elementary charge, and to identify the cleanness of electronic band gaps as s/S matches with e.

DOI: 10.1103/rq83-rwk2

Transcript

Introduction to the show: ident: Quantum Radio. Generated commentary on the latest quantum physics and condensed matter papers.

Kai: Today's paper: "Entropy-Seebeck ratio as a tool for elementary charge determination".

Mira: The gist: The ratio of differential entropy per particle to the Seebeck coefficient converges to the elementary charge across an energy window in gapped armchair silicene nanoribbons,

Kai: First, who's behind it and why it matters.

Paper summary: Kai: So looking at the paper "Entropy-Seebeck ratio as a tool for elementary charge determination" the authors show that by tracking this s over S ratio they get a direct estimate of the elementary charge e around room temperature in armchair silicene nanoribbons.

Mira: What this means is that you have a thermodynamic alternative to traditional transport calculations for estimating charge carriers and it gives us insight into how clean those band gaps are when that ratio matches e.

Lev: The real implication for hardware research is understanding where the limitations lie they flagged that this relationship only holds precisely in specific spectral regimes and it becomes undefined for gapless ribbons near zero energy.

Kai: So if you're building quantum hardware knowing which ribbon widths fall into those stable regimes helps you predict the accuracy of your charge carrier characterization using these entropy-based metrics.

Mira: It’s a way to look at transport and thermodynamics from two different angles one focusing on energy transmission and the other on electronic entropy and seeing them converge is what makes this paper important.

Lev: The paper shows that while it’s a tool you still need to be careful about the assumptions they made regarding spectral weights being proportional or vanishing in the same energy window for Equation five to hold <ref:2508.15067#pg2>.

Kai: It gives us a practical route to estimate charge fluctuations at finite temperatures which is something we really need when dealing with real materials that aren't perfectly isolated.

Conclusion: Kai: So, we've looked at how armchair silicene nanoribbons use the ratio of differential entropy per particle to the Seebeck coefficient to get an estimate of elementary charge around room temperature.

Mira: That ratio essentially connects transport properties, which is what S measures through energy dependence of transmission, with thermodynamic properties that relate to electronic entropy.

Lev: What this means for us is a new way to estimate charge carriers without needing super complex explicit transport calculations when you're working with these two-dimensional systems.

Kai: The authors show that for specific ribbon widths, say those in the semiconducting regime, this ratio converges to the elementary charge e across an energy window.

Mira: That convergence happens because the spectral weights involved in both quantities are either proportional or they vanish within that specific energy range.

Lev: They use different ribbon widths to show you where you'll see metallic behavior versus semiconducting behavior, which helps define those regimes clearly.

Kai: They also point out that for gapless ribbons near zero energy, this ratio becomes undefined, which is a big caveat for applying this method broadly.

Mira: So the main implication here is using this thermodynamic route to probe the electronic structure and potentially characterize band gaps more cleanly.

Lev: The paper gives us a way to see how clean those band gaps are when that ratio actually matches e.

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