Effects of uniaxial and hydrostatic pressure on the valence band maximum inSb2Te3: An electronic structure study
Effects of uniaxial and hydrostatic pressure on the valence band maximum inSb2Te3: An electronic structure study
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DOI：
10.1103/physrevb.74.205113
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发表时间：
2006-11
影响因子：
3.7
通讯作者：
P. Larson
中科院分区：
文献类型：
--
作者：
P. Larson
，以合金的形式，构成了室温热电材料的基础。虽然实验压力研究已经研究了热电性质的变化，但很少有理论研究研究能带结构如何随压力变化。为了了解价带最大值的性质，已经进行了电子结构计算。我们使用了之前在另一组作者的作品中在压力下松弛的晶格常数和原子位置。使用这些值，我们发现价带最大值随压力的变化而发生显着变化，这是之前的作者没有研究的。价带最大值位于通常绘制的高对称线之外。静水压力显示价带最大值的位置变化非常小，但当单轴施加压力时会发生深刻的变化。价带最大值从一个离轴位置移动到另一个离轴位置，使得围绕多个价带最大值出现，这可以增强热电性能。这个新峰的有效质量更大，与轻空穴上价带（UVB）和重空穴下价带（LVB）的存在一致。这种电子拓扑转变可以解释通过增加能带简并性和有效质量而导致热电特性随着周围单轴压力而显着增加。
, in the form of alloys withand, forms the basis of room temperature thermoelectric materials. While experimental pressure studies have investigated changes to thermoelectric properties, few theoretical investigations have examined how the band structure changes as a function of pressure. Electronic structure calculations have been performed onin order to understand the nature of the valence band maximum. We used lattice constants and atomic positions which have previously been relaxed under pressure in a work by another set of authors. Using these values we find significant changes to the valence band maximum as a function of pressure which the previous authors did not investigate. The valence band maximum lies off of the high symmetry lines which are usually plotted. Hydrostatic pressure shows very little change in the position of the valence band maximum up to, but a profound shift occurs when pressure is applied uniaxially. The valence band maximum shifts from one off-axis position to another by, so that aroundmultiple valence band maxima occur which may enhance the thermoelectric properties. The effective masses of this new peak are larger, consistent with the existence of a light-hole upper valence band (UVB) and a heavy-hole lower valence band (LVB). This electronic topological transition may explain the significant increase seen in the thermoelectric properties ofas a function of uniaxial pressure aroundby increasing both the band degeneracy and effective masses.