化学衍生多层石墨烯在毫特斯拉磁场下的大能斯特效应
Large Nernst effect in chemically derived multilayer graphene at millitesla magnetic fields
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中文总结 AI 辅助
本研究在化学衍生多层石墨烯薄膜中观察到毫特斯拉磁场下的大能斯特效应，横向热电势可达250 μV/K，展示了其用于热电发电的潜力。
中文摘要 AI 辅助
石墨化合物的简单合成、高导电性以及与其他材料的可集成性，推动了基于石墨的热电发电机的研发。同时，石墨和石墨烯的半金属特性导致电子-空穴补偿，使得热电势几乎为零。在此，我们观察到在低磁场$B$下，具有厚度和载流子密度强烈波动的化学衍生多层石墨烯薄膜中产生大的横向热电势。利用扫描激光诱导宏观薄膜加热，我们发现横向（能斯特）热电电压在金属掺杂石墨烯接触处，在$B^*\approx4$ mT和环境条件下变得与纵向热电电压相当。基于已知激光诱导温度的横向热电势$S_{xy}$估算表明，在$B^*$处其大小约为$\sim 10$ $\mu$V/K，并以亚线性方式上升至在$B\approx315$ mT（我们使用厘米级永磁体达到的最大磁场）时的250 $\mu$V/K。当直流磁场线与局部能斯特电流同向时，在霍尔探针处测量电压可获得额外的热电信号增强。我们的结果表明，大规模多层石墨烯在热电发电方面具有应用前景。
英文摘要
Simple synthesis of graphitic compounds, their high conductivity, and integrability with other materials motivate the effort toward graphite-based thermoelectric generators. At the same time, semimetallic nature of graphite and graphene results in nearly-zero thermopower due to electron-hole compensation. Here, we observe large transverse thermopower in chemically derived multilayer graphene films with strong fluctuations of thickness and carrier density at low magnetic fields $B$. Using the scanning laser-induced heating of macroscopic film, we find that transverse (Nernst) thermoelectric voltage becomes comparable to the longitudinal thermoelectric voltage at the metal-doped graphene contact at $B^*\approx4$ mT and ambient conditions. Estimates of transverse thermopower $S_{xy}$ based on the known laser-induced temperature show that it is as large as $\sim 10$ $μ$V/K at $B^*$, and raises in a sub-linear fashion to 250 $μ$V/K at $B\approx315$ mT, the maximum field we reach with centimeter-sized permanent magnet. Extra increase in thermoelectric signal is achieved upon voltage measurement at Hall probes when the dc field lines are co-directional with local Nernst current. Our results show the promise of large-scale multilayer graphene for thermoelectricity generation.
发表机构
- Moscow Institute of Physics and Technology（莫斯科物理技术学院）
- Joint-Stock Company ”Skanda Rus”（斯坎达鲁斯股份公司）
- National Research Nuclear University “MEPhI”（国立核研究大学“莫斯科工程物理学院”）
- Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences（俄罗斯科学院微电子技术与高纯材料研究所）
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