We present a study of the thermoelectric (Seebeck and Nernst) response in heavily overdoped, non-superconducting La_1.67Sr_0.33CuO₄. In spite of the electron-like curvature of the Fermi surface, the Seebeck coefficient is positive at low temperatures. Such a feature, previously observed in copper, silver, gold and lithium, is caused by a non-trivial energy dependence of the scattering time. We argue that this feature implies a strong asymmetry between the lifetime of occupied and unoccupied states along the zone diagonals and such an electron–hole asymmetry impedes formation of Cooper pairs along the nodal direction in the superconducting ground state emerging at lower doping levels.

中文翻译：

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高掺杂La2-xSrxCuO4中的塞贝克系数为正（x = 0.33）; 它的起源和寓意

我们对重掺杂，非超导La _1.67 Sr _0.33 CuO ₄中的热电（Seebeck和Nernst）响应进行了研究。尽管费米表面具有类似电子的曲率，但塞贝克系数在低温下仍为正。先前在铜，银，金和锂中观察到的这种特征是由散射时间的非平凡能量依赖性引起的。我们认为，该特征暗示了沿区域对角线的处于占用状态和未占用状态的寿命之间存在强烈的不对称性，并且这种电子-空穴不对称性阻止了在低掺杂水平出现的超导基态中沿结点方向形成库珀对。