Irradiation of strong light on a material leads to numerous nonlinear effects that are essential to understand the physics of excited states of the system and optoelectronics. Here, we study the nonlinear thermoelectric effects due to the electric and thermal fields applied on a noncentrosymmetric system. The phenomenon arises on the Fermi surface with the transitions of electrons from the valence to conduction bands. We derive the formalism to investigate these effects and find that the nonlinearity in these effects, namely, nonlinear Seebeck and nonlinear Peltier effects, depends on the ratio of the nonlinear to linear conductivities. The theory is tested for a hexagonally warped and gapped topological insulator. Results show enhancement in the longitudinal and Hall effects on increasing the warping strength but show opposite behavior with the surface gap.

中文翻译：

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对拓扑绝缘子中非线性热电效应的内在贡献

在材料上照射强光会导致许多非线性效应，这对于理解系统和光电子的激发态的物理特性是必不可少的。在这里，我们研究由于非中心对称系统上施加的电场和热场而产生的非线性热电效应。这种现象出现在费米表面上，电子从价态跃迁到导带。我们导出形式主义来研究这些效应，发现这些效应中的非线性，即非线性塞贝克效应和非线性珀尔帖效应，取决于非线性电导率与线性电导率的比值。该理论已针对六边形翘曲和带间隙的拓扑绝缘子进行了测试。