Charge compensation in extremely large magnetoresistance materials LaSb and LaBi revealed by first-principles calculations
Charge compensation in extremely large magnetoresistance materials LaSb and LaBi revealed by first-principles calculations
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第一性原理计算揭示超大磁阻材料LaSb和LaBi的电荷补偿
DOI：
10.1103/physrevb.93.235142
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发表时间：
2016-06-21
影响因子：
3.7
通讯作者：
Lu, Zhong-Yi
中科院分区：
文献类型：
--
作者：
Guo, Peng-Jie;Yang, Huan-Cheng;Lu, Zhong-Yi
采用第一性原理电子结构计算方法，系统地研究了新近发现的超大磁电阻材料LaSb和LaBi的电子结构。我们发现LaSb和LaBi都是电子和空穴载流子平衡的半金属。计算得到的载流子密度为${10}^{20}\phantom{\rule{0.28em}{0 ex}}{\mathrm{cm}}^{\ensuremath{-}3}$，与实验值吻合较好，这意味着低温下载流子的平均自由时间较长，因而载流子迁移率较高。用半经典的两带模型，电荷补偿和高载流子迁移率自然地解释了：（i）在LaSb和LaBi中观察到的XMR，（ii）XMR对外部磁场的非饱和二次依赖性，以及（iii）在非常低的温度下导通温度行为中的电阻率平台。不借助拓扑效应对这些特征进行解释表明，它们应该是所有电子空穴补偿半金属的共同特征。
By the first-principles electronic structure calculations, we have systematically studied the electronic structures of recently discovered extremely large magnetoresistance (XMR) materials LaSb and LaBi. We find that both LaSb and LaBi are semimetals with the electron and hole carriers in balance. The calculated carrier densities on the order of ${10}^{20}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$ are in good agreement with the experimental values, implying long mean-free time of carriers at low temperatures and thus high carrier mobilities. With a semiclassical two-band model, the charge compensation and high carrier mobilities naturally explain: (i) the XMR observed in LaSb and LaBi, (ii) the nonsaturating quadratic dependence of XMR on an external magnetic field, and (iii) the resistivity plateau in the turn-on temperature behavior at very low temperatures. The explanation of these features without resorting to the topological effect indicates that they should be the common characteristics of all electron-hole compensated semimetals.