Thermopower and Nernst measurements in a half-filled lowest Landau level
Thermopower and Nernst measurements in a half-filled lowest Landau level
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DOI：
10.1103/physrevb.97.245425
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发表时间：
2018-06-28
影响因子：
3.7
通讯作者：
Du, Rui-Rui
中科院分区：
文献类型：
--
作者：
Liu, Xiaoxue;Li, Tingxin;Du, Rui-Rui
受到波特等人最近提出的建议的激励。[物理。X6,031026(031026)][关于狄拉克复合费米子可能的热电特征，我们对填充因子v=1/2时超高迁移率的GaAs/AlxGa1-xAs二维电子系统的热电输运进行了系统的实验研究。我们证明了热电势S-xx和能斯特S-xy关于B=0T分别是对称和反对称的。在v=1/2时测量的热电偶S-xx的性能与以前的实验结果是一致的。V=1/2的能斯特信号S-XY为非零能斯特信号，在声子拖曳占主导地位的区域与温度呈幂函数关系。在电子扩散占优势的区域，发现v=1/2的能斯特信号S-xy比Potter等人预测的线性温度相关值小得多，而且随温度下降的速度比线性相关快。
Motivated by the recent proposal by Potter et al. [Phys. Rev. X 6, 031026 (2016)] concerning possible thermoelectric signatures of Dirac composite fermions, we perform a systematic experimental study of thermoelectric transport of an ultrahigh-mobility GaAs/AlxGa1-xAs two-dimensional electron system at filling factor v = 1/2. We demonstrate that the thermopower S-xx and Nernst S-xy are symmetric and antisymmetric with respect to B = 0 T, respectively. The measured properties of thermopower S-xx at v = 1/2 are consistent with previous experimental results. The Nernst signals S-xy of v = 1/2, which have not been reported previously, are nonzero and show a power-law relation with temperature in the phonon-drag dominant region. In the electron-diffusion dominant region, the Nernst signals S-xy of v = 1/2 are found to be significantly smaller than the linear temperature dependent values predicted by Potter et al., and decreasing with temperature faster than linear dependence.