SnTe中菱面体畸变引起的费米面拓扑变化
Changes of Fermi Surface Topology due to the Rhombohedral Distortion in SnTe
摘要：
理论上，化学计量的SnTe是一种小禁带半导体，在冷却时会发生铁电畸变。然而，在现实中，晶体总是非化学计量的和金属的;因此，铁电转变更准确地描述为极性结构转变。在这里，我们研究费米面使用量子振荡作为压力的函数。我们发现在高压下，由于极性跃迁的抑制，振荡谱发生了变化，并且小于10 kbar就足以稳定无畸变的立方晶格。这伴随着霍尔和电阻率的大幅下降。结合我们的密度泛函理论（DFT）计算和角度分辨光电子能谱（ARPES）测量，这表明费米表面$L$ -口袋有较低的流动性比管状费米表面连接它们。在我们的DFT计算中还捕获到极性相的带隙和态密度的小的加宽。此外，我们发现了不寻常的现象，存在的线性磁电阻，而不管我们归因于区域的费米表面的高曲率的扭曲。
英文摘要：
Stoichiometric SnTe is theoretically a small gap semiconductor that undergoes a ferroelectric distortion on cooling. In reality however, crystals are always non-stoichiometric and metallic; the ferroelectric transition is therefore more accurately described as a polar structural transition. Here we study the Fermi surface using quantum oscillations as a function of pressure. We find the oscillation spectrum changes at high pressure, due to the suppression of the polar transition and less than 10 kbar is sufficient to stabilize the undistorted cubic lattice. This is accompanied by a large decrease in the Hall and electrical resistivity. Combined with our density functional theory (DFT) calculations and angle resolved photoemission spectroscopy (ARPES) measurements this suggests the Fermi surface $L$-pockets have lower mobility than the tubular Fermi surfaces that connect them. Also captured in our DFT calculations is a small widening of the band gap and shift in density of states for the polar phase. Additionally we find the unusual phenomenon of a linear magnetoresistance that exists irrespective of the distortion that we attribute to regions of the Fermi surface with high curvature.
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