The longitudinal magnetoresistance (MR) is assumed to be hardly realized as the Lorentz force does not work on electrons when the magnetic field is parallel to the current. However, in some cases, longitudinal MR becomes large, which exceeds the transverse MR. To solve this problem, we have investigated the longitudinal MR considering multivalley contributions based on the classical MR theory. We have showed that the large longitudinal MR is caused by off- diagonal components of a mobility tensor. Our theoretical results agree with the experiments of large longitudinal MR in IV-VI semiconductors, especially in PbTe, for a wide range of temperatures, except for linear MR at low temperatures.

中文翻译：

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多谷系统的大纵向磁阻

当磁场与电流平行时，由于洛伦兹力对电子不起作用，因此假定纵向磁阻 (MR) 很难实现。然而，在某些情况下，纵向 MR 变大，超过横向 MR。为了解决这个问题，我们基于经典 MR 理论研究了考虑多谷贡献的纵向 MR。我们已经表明，大的纵向 MR 是由移动张量的非对角线分量引起的。我们的理论结果与 IV-VI 半导体中大纵向 MR 的实验一致，特别是在 PbTe 中，除了低温下的线性 MR 外，在很宽的温度范围内。