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arXiv 1603.04414cond-mat.mtrl-sci
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用密度泛函理论和Shubnikov-de Haas测量研究Na掺杂PbTe的费米面演化

Fermi surface evolution of Na-doped PbTe studied through density functional theory calculations and Shubnikov-de Haas measurements

P. Giraldo-Gallo, B. Sangiorgio, P. Walmsley, M. Fechner, S. C. Riggs, T. H. Geballe, N. A. Spaldin, I. R. Fisher

摘要:

我们提出了一个相结合的实验和理论研究的低温费米面的碲化铅,碲化铅,空穴引入时,通过钠取代铅网站的演变。我们的Shubnikov-de-Haas测量适用于载流子浓度高达$9.4\times10^{19}$ cm $^{-3}$的样品(0.62 Na原子$\%$)的费米面演化的定性特征(拓扑结构和有效质量),通过我们在广义梯度近似(GGA)内的密度泛函(DFT)计算预测:我们在低和中等载流子浓度下获得了完美的椭圆形L-口袋,对于所研究的最高掺杂,回旋有效质量随掺杂浓度单调增加,表明在整个能带中偏离了理想抛物线。然而,我们的测量结果表明,标准的DFT计算低估了L点和$Σ$ -线价带最大值之间的能量差,因为我们的数据是一致的,在整个掺杂范围内的研究,而计算预测的$Σ$ -口袋在更高的掺杂占领一个单一的费米表面口袋的占领。我们的结果为低和中间的组合物是一致的非抛物线凯恩模型的色散,其中的L-口袋是固定的各向异性在整个频带的椭球体,但有效质量强烈依赖于费米能量。

英文摘要:

We present a combined experimental and theoretical study of the evolution of the low-temperature Fermi surface of lead telluride, PbTe, when holes are introduced through sodium substitution on the lead site. Our Shubnikov-de-Haas measurements for samples with carrier concentrations up to $9.4\times10^{19}$cm$^{-3}$ (0.62 Na atomic $\%$) show the qualitative features of the Fermi surface evolution (topology and effective mass) predicted by our density functional (DFT) calculations within the generalized gradient approximation (GGA): we obtain perfect ellipsoidal L-pockets at low and intermediate carrier concentrations, evolution away from ideal ellipsoidicity for the highest doping studied, and cyclotron effective masses increasing monotonically with doping level, implying deviations from perfect parabolicity throughout the whole band. Our measurements show, however, that standard DFT calculations underestimate the energy difference between the L-point and $Σ$-line valence band maxima, since our data are consistent with occupation of a single Fermi surface pocket over the entire doping range studied, whereas the calculations predict an occupation of the $Σ$-pockets at higher doping. Our results for low and intermediate compositions are consistent with a non-parabolic Kane-model dispersion, in which the L-pockets are ellipsoids of fixed anisotropy throughout the band, but the effective masses depend strongly on Fermi energy.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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