Joule heating and the thermal conductivity of a two-dimensional electron gas at cryogenic temperatures studied by modified 3$\omega$ method
| Autor: | Akira Endo, Shingo Katsumoto, Yasuhiro Iye |
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| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: | |
| Popis: | During the standard ac lock-in measurement of the resistance of a two-dimensional electron gas (2DEG) applying an ac current $I = \sqrt{2} I_0 \sin(\omega t)$, the electron temperature $T_e$ oscillates with the angular frequency $2 \omega$ due to the Joule heating $\propto I^2$. We have shown that the highest ($T_\mathrm{H}$) and the lowest ($T_\mathrm{L}$) temperatures during a cycle of the oscillations can be deduced, at cryogenic temperatures, exploiting the third-harmonic (3$\omega$) component of the voltage drop generated by the ac current $I$ and employing the amplitude of the Shubnikov-de Haas oscillations as the measure of $T_e$. The temperatures $T_\mathrm{H}$ and $T_\mathrm{L}$ thus obtained allow us to roughly evaluate the thermal conductivity $\kappa_{xx}$ of the 2DEG via the modified 3$\omega$ method, in which the method originally devised for bulk materials is modified to be applicable to a 2DEG embedded in a semiconductor wafer. The $\kappa_{xx}$ thus deduced is found to be consistent with the Wiedemann-Franz law. The method provides a convenient way to access $\kappa_{xx}$ using only a standard Hall-bar device and the simple experimental setup for the resistance measurement. Comment: Main text: 10 pages, 5 figures. Supplementary material: 4 pages, 6 figures, minor revision |
| Databáze: | OpenAIRE |
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