热电材料中的涨落-耗散
Fluctuation-Dissipation in Thermoelectrics
AI总结：
该研究将Johnson-Nyquist噪声公式推广至热电领域，推导得出热截止频率下增强的电压涨落谱密度公式，并通过集成热电微型器件实验验证，证实热电器件可用于测量涨落-耗散定理描述的基本温度涨落。
摘要：
热电材料表现出电荷与热的关联输运。描述电压涨落谱密度的Johnson-Nyquist噪声公式$4 k_B T R$仅解释了与欧姆耗散相关的涨落。应用涨落-耗散定理，我们将Johnson-Nyquist公式推广到热电领域，发现在热截止频率$f_T$以下的频段，电压涨落谱密度增强为$4 k_B T R (1 + ZT)$，其中$ZT$是无量纲的热电材料优值。电压噪声增强的根源是温度涨落的热电耦合。我们使用一款宽带（$f_T\thicksim1$ kHz）集成热电微型器件通过实验验证了我们的发现。通过测量经$ZT$增强的电压噪声，我们在295 K的平均温度下，实验分辨出振幅为$0.8~\u03bc\rm K\rm Hz^{-1/2}$的温度涨落。我们发现，热电器件可用于测温，其分辨率足以测量涨落-耗散定理所描述的基本温度涨落。
英文摘要：
Thermoelectric materials exhibit correlated transport of charge and heat. The Johnson-Nyquist noise formula $ 4 k_B T R $ for spectral density of voltage fluctuations accounts for fluctuations associated solely with Ohmic dissipation. Applying the fluctuation-dissipation theorem, we generalize the Johnson-Nyquist formula for thermoelectrics, finding an enhanced voltage fluctuation spectral density $4 k_B T R (1 + ZT)$ at frequencies below a thermal cut-off frequency $f_T$, where $ZT$ is the dimensionless thermoelectric material figure of merit. The origin of the enhancement in voltage noise is thermoelectric coupling of temperature fluctuations. We use a wideband ($f_T\sim1$ kHz), integrated thermoelectric micro-device to experimentally confirm our findings. Measuring the $ZT$ enhanced voltage noise, we experimentally resolve temperature fluctuations with an amplitude of $0.8~μ\mathrm{K} \mathrm{Hz}^{-1/2}$ at a mean temperature of 295 K. We find that thermoelectric devices can be used for thermometry with sufficient resolution to measure the fundamental temperature fluctuations described by the fluctuation-dissipation theorem.
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