Refining the Two-Band Model for Highly Compensated Semimetals Using Thermoelectric Coefficients
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| Format: | Preprint |
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2024
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| _version_ | 1866916708337319936 |
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| author | Leahy, Ian Treglia, Andrew Cao, Gang Skinner, Brian Lee, Minhyea |
| author_facet | Leahy, Ian Treglia, Andrew Cao, Gang Skinner, Brian Lee, Minhyea |
| contents | In studying compensated semimetals, the two-band model has proven extremely useful in capturing electrical conductivity under magnetic field, as a function of density and mobility of electron-like and hole-like carriers. However, it rarely offers practical insight into magneto-thermoelectric properties. Here, we report the field dependence of thermoelectric (TE) coefficients in a highly compensated semimetal NbSb$_2$, where we find the Seebeck and Nernst coefficients increase quadratically and linearly with applied magnetic field, respectively. Such field dependence was predicted in previous work that studied a system of two parabolic bands, within semiclassical Boltzmann transport theory when the following two conditions are simultaneously met:$ω_cτ\gg 1$ and $\tanθ_H \ll 1$. Under these conditions, we find the field dependence of the TE coefficients directly provides a relation between the electron-like ($n_e$) and hole-like ($n_h$) carrier densities, which in turn can be used to refine two-band model fitting. With this, we find the compensation factor ($\frac{|Δn|}{n_e}$) of NbSb$_2$ is two orders of magnitude smaller than what was found in unrestricted fitting, resulting in a larger saturation field scale for magnetoresistance. Within the same framework of the semiclassical theory, we also deduce that the thermoelectric Hall angle $\tanθ_γ = \frac{S_{xy}}{S_{xx}}$ can be expressed as $\big(\frac{|Δn|}{n_e} \times ω_cτ\big)^{-1}$, which serves as a parameter to predict the degree of compensation. Our findings offer crucial insights into identifying empirical conditions for field-induced enhancement of TE performance and into engineering efficient thermoelectric devices based on semimetallic materials. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2412_17688 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Refining the Two-Band Model for Highly Compensated Semimetals Using Thermoelectric Coefficients Leahy, Ian Treglia, Andrew Cao, Gang Skinner, Brian Lee, Minhyea Strongly Correlated Electrons Materials Science In studying compensated semimetals, the two-band model has proven extremely useful in capturing electrical conductivity under magnetic field, as a function of density and mobility of electron-like and hole-like carriers. However, it rarely offers practical insight into magneto-thermoelectric properties. Here, we report the field dependence of thermoelectric (TE) coefficients in a highly compensated semimetal NbSb$_2$, where we find the Seebeck and Nernst coefficients increase quadratically and linearly with applied magnetic field, respectively. Such field dependence was predicted in previous work that studied a system of two parabolic bands, within semiclassical Boltzmann transport theory when the following two conditions are simultaneously met:$ω_cτ\gg 1$ and $\tanθ_H \ll 1$. Under these conditions, we find the field dependence of the TE coefficients directly provides a relation between the electron-like ($n_e$) and hole-like ($n_h$) carrier densities, which in turn can be used to refine two-band model fitting. With this, we find the compensation factor ($\frac{|Δn|}{n_e}$) of NbSb$_2$ is two orders of magnitude smaller than what was found in unrestricted fitting, resulting in a larger saturation field scale for magnetoresistance. Within the same framework of the semiclassical theory, we also deduce that the thermoelectric Hall angle $\tanθ_γ = \frac{S_{xy}}{S_{xx}}$ can be expressed as $\big(\frac{|Δn|}{n_e} \times ω_cτ\big)^{-1}$, which serves as a parameter to predict the degree of compensation. Our findings offer crucial insights into identifying empirical conditions for field-induced enhancement of TE performance and into engineering efficient thermoelectric devices based on semimetallic materials. |
| title | Refining the Two-Band Model for Highly Compensated Semimetals Using Thermoelectric Coefficients |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2412.17688 |